Читать книгу Tri-nitro-glycerine, as Applied in the Hoosac Tunnel, Submarine Blasting, etc., etc., etc - George M. Mowbray - Страница 5

Table of Contents

Nitro-Glycerin—Introduction of the explosive in New York, San Francisco, Lake Superior, and the Hoosac Tunnel, Massachusetts. Accidents, Reports of Engineers Thos. A. Doane, W. P. Granger and B. D. Frost, of the Manufacturer, Miners’ statement.

The city of New York was startled one fine Sunday morning (1865) by an explosion in Greenwich Street, opposite the Wyoming Hotel, the windows of every house within one hundred yards of the entrance to the Wyoming Hotel were shattered, pedestrians were thrown down, and the pavement broken up. A few minutes previous to the explosion, one of the guests in the hotel had been engaged polishing his boots; for this purpose he had drawn from under the counter of the hotel office a small box, on which he had rested his foot; noticing a reddish vapor emanating from there, he drew the attention of the hotel clerk to it, who taking the box in his hands made his way to the front door and threw it into the gutter, whereupon explosion instantly followed.

An investigation of the circumstances connected with the storage of this box, developed the following facts: Some time previously a passenger from Germany who had occupied a room at the hotel, being unsuccessful in obtaining employment had left it as security for his board, stating that it was Glonoin Oil, a new material that had been used in Germany for blasting purposes with great success, that he, the passenger, had been entrusted with an agency for introducing the same to miners and others, but had failed to get it introduced into use; undoubtedly the box contained Nitro-Glycerin, manufactured by the Nobel Brothers, who had a manufactory where this explosive was compounded, at Hamburgh.

In the early part of the year 1866 this substance was again a prominent subject of discussion, owing to an explosion which was attended with the burning and ultimate destruction of the steamer “European,” one of the West India mail packets, while she was lying at the railway wharf of Colon or Aspinwall, on the Atlantic side of the isthmus of Panama. Knowing that Nitro-Glycerin was on board under the name of “glonvene” or “glonoin oil,” on its way to the gold mining districts of the North American Pacific States, as an explosive or blasting agent, it was concluded that the explosion was due to this substance. Unfortunately, forty-seven persons were either killed at the time of the explosion or died shortly afterward from the injuries they sustained. Immediately succeeding this accident another explosion occurred in the office of Wells, Fargo & Co., in San Francisco, by which eight persons lost their lives. The damages by the explosion on board the “European” were estimated at one million dollars, for the vessel, built of iron and of unusual strength, was destroyed, and the pier with an upper railroad track for unloading cargo, and warehouses for storing freight, were completely wrecked. The San Francisco explosion involved a further loss of a quarter million dollars.

In all the above cases the Nitro-Glycerin manufactured at Hamburgh reached New York safely; in the Wyoming Hotel explosion it had been lying in the hotel several weeks, in the Aspinwall catastrophe it had been transported over the Isthmus and reshipped by steamer as express freight by Wells, Fargo & Co., to San Francisco, and carted to their office in Montgomery Street before the explosion occurred. It subsequently transpired that the immediate cause of the explosion at Aspinwall was a case slipping from the slings whilst being hoisted out of the hold of the vessel; in San Francisco, the circumstances as detailed to the writer, were as follows: a man passing by Wells, Fargo & Co.’s office heard one of the employee’s address a gentleman riding past on horseback, saying, “Doctor, we have got a case of glonoin oil and it seems to be smoking, I wish you would step in and advise us what had better be done with it;” the doctor (Hill) dismounted, requesting a passer-by to take charge of his horse and walk it up and down the block, the animal being too high spirited to stand without an attendant; scarcely had the person in charge gone a block from the office when the explosion occurred. It can only be inferred that in breaking open the case to discover the cause of leakage of red fumes, the Nitro-Glycerin was exploded. I have since ascertained from the New York consignee of this parcel of Nitro-Glycerin, (Messrs. Nobel’s agent) that after the shipment to Panama, which was only a part of the consignment from Hamburgh, the agent leaving another portion in warehouse in Tenth Street, New York, proceeded to Lake Superior in the winter season with a part of the same shipment, where, on arrival and opening the cases, he found it had been packed in bottles surrounded with sawdust, and in congealing had burst the bottles, a portion of the Nitro-Glycerin being found solid in the neck of the bottle. This therefore, if correctly reported, would go to prove the Nobel Nitro-Glycerin expands during congelation.[1] What had been bottles containing Nitro-Glycerin were now fragments of broken glass, whilst the Nitro-Glycerin itself, owing to the extremely cold temperature of a Lake Superior winter, was found in solid mass of the exact mould of the bottle that had contained it. Upon discovering this condition of the cases and their contents the consignee at Lake Superior telegraphed to his correspondent in New York: “Direct Messrs. Bandmann to throw the cases of Nitro-Glycerin, shipped to them, overboard on arrival.” Probably in the belief that the temperature of the upper lakes was the cause of the broken bottles and that the warmer temperature of the tropics and San Francisco did not apply, this advice was neglected.

Reflecting as a chemist upon these explosions, that here was a compound made at Hamburgh, carted to the wharf, loaded on board steamer by the stevedores, voyaging to London, reshipped to Panama, the express portion of it forwarded across the Isthmus by railway, thence lightered to and loaded upon the steamer, bearing twelve days’ voyage to San Francisco, where on arrival it is taken to the express office, previous to being forwarded to the mines; now how did it happen, since there is no effect without a cause, after all this handling that an explosion took place? Determined to solve this problem, I undertook the preparation and qualitative examination of Nitro-Glycerin. Residing at that time at Titusville in the oil region of Pennsylvania, where the disastrous results of speculations in oil territory during the previous year, compelled most of us to “masterly inactivity,” I had the leisure, whilst my curiosity was piqued to discover, the apparently anomalous properties which this explosive seemed to present, and in 1866, after maturing the process patented April 7, 1868, I inserted a brief advertisement in the Scientific American, offering to manufacture Nitro-Glycerin on a large scale for miners and others. In 1866, I received a communication from Thomas A. Doane, Esq., chief engineer of the Hoosac Tunnel, who was keenly alive to the necessity of more efficient means for driving that work. I extract from his annual report to the Commissioners of the Troy and Greenfield Railroad and Hoosac Tunnel, James M. Shute, Alvah Crocker and Charles Hudson, dated Dec. 19, 1866, and having reference to the work of the current year, as follows:

“Page 21. It has been my continual desire since entering upon this work to learn how to fire several charges at the same time. This I hoped to do of Colonel Tal P. Shaffner, but his coming upon our work was so long delayed, it being something more than a year after his first brief visit here, that it began to seem hopeless. Last spring, in making a visit to the Bessemer steel works in Troy, partly in way of business, but more out of curiosity to see and learn something concerning this process of making steel, it was my good fortune to obtain an introduction through Mr. Holley of the steel works, to J. J. Revey of London. Mr. Revey is connected with the gun-cotton works of London, and was acquainted with the most approved methods of simultaneous firing. He very kindly and fully explained to me the process and gave me a description of the electrical machine and fuses necessary, and also afterwards made a visit to our Tunnel. The Commissioners ordered for me two electric machines, four thousand fuses, and several miles of conducting and connecting wire. These were several months in transit and before their arrival Colonel Shaffner came with his material. His machine for exploding was Wheatstone’s magneto-electric exploder, and by it and his system of connecting wires it was found impossible to fire more than about five charges at once, and these not simultaneously. This of course was far from satisfactory. Shortly after, the ebonite (or Austrian pattern) machines with the Abel fuses ordered for me, arrived, and we very soon learned how to use them both, and have been able to fire at once as many as thirty-one charges.

“While it is important to save the time which can be saved by this process in firing, and to reduce the risk of accident, and to avoid the smoke made by the burning of the common fuse, it is much more important to the progress that simultaneity of firing be secured. If charges in adjoining holes can be fired as though but one charge, then they help each other and much more rock will be torn away. The whole top may be thrown down or the bottom brought up by proper arrangement of holes, and by means of a ring of converging holes the center may be dragged out. The passage of the electric spark through one system of wires occupies practically no appreciable time, while through several systems it may. If the charges in adjoining holes are fired with the interval of an instant, it may just as well be a week so far as the tearing of the rock is concerned.

“The number of fuses obtained was so small that their influence upon progress is hardly appreciable, except possibly at the Central Shaft.

“Under the direction of Colonel Shaffner, experiments have been tried at the West Shaft with Nitro-Glycerin. The article used was imported from Europe, and much time was consumed in ordering, shipping, and passing it through the custom house. In these experiments Colonel Shaffner has been eminently successful. No accident has resulted, and indeed there seems to be comparatively little risk if the article is good and ordinary care is taken in its use.

“The Glycerin will occasion to some persons, if they are exposed to it in a particular manner, a headache[2] for an hour or two, while others are not thus affected. Our men have made very little complaint in this respect, and indeed there has been no difficulty experienced in introducing this new and powerful explosive among men who never before have used anything but powder.

“It was some time ago demonstrated by experiment, that double progress could be made with Glycerin over that made with powder at less cost. This is a wonderful achievement and its effect upon the prospect of this work, in regard to its early completion at reasonable cost cannot but be good. It is true that the experiment was limited to a shorter time by reason of the small supply of electrical fuses and Nitro-Glycerin than could have been wished, and that my views may upon further experience be modified or changed even, but with what information I now have there is no room to doubt its fitness for our purpose. It is the testimony of all who have seen our work, including Mr. Revey, George Berkeley of London, C. E., Dr. Erhardt of London, Colonel Shaffner, and others familiar with tunnelling, that while our rock is not in general harder to drill than many others, it is most persistently tough. That is, the number of charges we fire, if they could be in granite or lime or in any brittle stone, would bring out two or three times more of debris than now. It is therefore necessary that we should have the quickest explosive to get the best result. As preparations of mercury are not to be thought of on account of their danger, we take Nitro-Glycerin as being next in power, while it is comparatively safe. Whenever its extensive use shall be concluded upon it will be necessary to secure the services of some scientific person expert in handling it, that some antidote against headache may be discovered, and that the risk may be reduced to the lowest possible point. Bulk for bulk, which is the only useful comparison to be made here, Nitro-Glycerin is eight times more powerful than common powder.”

In same report, page 64, the consulting engineer, Benj. H. Latrobe, states: “In the east heading of the West Shaft experiments with Nitro-Glycerin as an explosive were made with highly favorable results, as reported by the chief engineer who states, the forward progress in the heading proper (six by fifteen in section) as doubled, and in the heading enlargement (to ten and a half and fifteen) as trebled by this new agent when compared with gunpowder. He also reports $10.20 per cubic yard saved in the heading, and $3.64 in the enlargement, on a similar comparison with gunpowder, results certainly of the most encouraging character, and inviting to farther and persevering effort for the safe and successful use of the new explosive.”

The Commissioners themselves report—page 6: “The value and economy of Nitro-Glycerin as an explosive seems to have been fully demonstrated and the method of using it with safety to the employees appears to be the only question now undetermined. Its early introduction is very desirable and preparations are making to bring this about whenever it shall appear prudent to do so, since it is believed, on the strength of numerous experiments made in the tunnel at the West End, that by the use of this agent alone, as compared with gunpowder, the time required for completing the work may be greatly reduced.”

Between the issuing of the above report and that of 1867, circumstances led to the withdrawal of Mr. Doane from the Tunnel, and Commissioner Hon. Alvah Crocker personally undertook the superintendence of the work. In his report dated January, 1868, the following remarks occur:

“Nitro-Glycerin—experiments as made in the West Shaft as given by Mr. Doane and referred to by Hon. Tappan Wentworth, chairman of the Tunnel Committee of that year, induced early action by the Commission. As long ago as February last I visited New York, and spent several days in endeavoring to ascertain if the article had been made there, or in the vicinity, but to no purpose. Finding subsequently that the railroads refused absolutely to transport it, the matter rested until the first of July, when I addressed George M. Mowbray, Esq., of Titusville, operative chemist, and with the permission of the Commission he was called to North Adams and a contract concluded with him highly advantageous to the Commonwealth. As will appear in the appendix, the public will be gratified to learn that we are on the eve of giving it a fair trial.”

On the 29th of October, 1867, the writer arrived in North Adams and I subjoin my report to the superintending commissioner, dated January 11, 1868, and addressed to Hon. Alvah Crocker, Superintendent of Hoosac Tunnel:

“Sir: I avail myself of permission to report progress of the arrangement to introduce Nitro-Glycerin for the purpose of blasting in the Hoosac Tunnel, subject to the conditions imposed by you at an interview held in the engineer’s office, during the latter part of October, 1867. These conditions were—

“First. To conduct the operations with a strict regard to the safety of the miners, and to avoid all risks that might endanger the property of the State, connected with the Tunnel.

“Second. The outlay of capital for the necessary works to be defrayed at my own cost and expense.

“Third. That the Nitro-Glycerin should be supplied at current market rates, freight added; the State of Massachusetts furnishing a convenient site for the buildings, compressed air, and a supply of water, free of cost, and to give the subscriber a preference in consideration of his erecting the works adjacent to the Tunnel.

“The reasons that led to this arrangement were, that as the rock found in excavating the Tunnel was exceedingly tough, any increased progress or lineal advance per month without any increased expenditure; in other words, diminished cost per lineal foot and quickened advance, seemed possible only by the use of a more effective explosive agent than gunpowder; that in Nitro-Glycerin this greater power existed, and therefore its use was desirable; the problem being convenience of supply, guarding against the possibility of accident, by planning carefully every detail in its use, rigidly enforcing every precaution, a failure in any of these points involving pecuniary loss in outlay for the works by the party undertaking its supply and superintending its use in the Tunnel.

“Agreeing with you in the propriety of these views, I commenced operations on the 30th of October. During the past two months a convenient two-story factory has been erected, and the necessary apparatus set up therein, about 1000 feet south of the west shaft; within twenty feet of this factory, a small dwelling for myself and an experienced assistant, and about 500 feet further south on the extreme line of land owned by the State, a magazine for storing Nitro-Glycerin has been constructed. Inclement weather somewhat retarded these operations, nevertheless, the crude articles used in the manufacture and every appliance to render the labor of making a “chemically pure” Nitro-Glycerin, without danger to those engaged in its manufacture, were completed and in good working order on the 31st of December, 1867.

“The assistance rendered me by the gentlemen superintending the various departments of the tunnel work, materially contributed to this result, and I gratefully acknowledge their uniform courtesy and promptitude in forwarding my undertaking. Your own constant attendance at the engineer’s office permitted me almost daily to submit my plans, which therefore met no delay in being subjected to the scrutiny of the engineer in charge, who as promptly reported on them.

“On the 2d of January, 1868, I moved up to the works and on the following day tested the apparatus by manufacturing, and although somewhat delayed by the necessity of drying the plastering in the magazine, and introducing suitable heating apparatus to maintain a moderate temperature during this inclement season, (a neglect of which precaution remotely led to the Bergen accident) yet to-day we have a supply of Nitro-Glycerin, properly and safely stored, ready for use. Samples of this have been duly tested for its explosive force by the engineer in charge and his assistant, giving satisfaction as to its tremendous power, and facility of explosion, with a peculiar fuse and exploder. You may therefore rely on a regular supply as needed, and I submit that a month’s consumption be kept on hand, in order that it may free itself from adherent water, which, except other means be used to free it, does not separate for about ten days. Freed from this obstinately adhering moisture, it is safer and more effective for blasting purposes.

“As respects its application to blasting, during the ensuing week the conducting wires will be laid to the east heading (west shaft) and in order to maintain the electrical machine in working order, I have arranged that the act necessary to firing a blast shall be performed in the time-keeper’s office, where the air is dry and therefore favorable to exciting the charge of electricity, but the control and the means to signal for a discharge, will be in the Tunnel at a safe distance from the heading. By this arrangement, although requiring more conducting wire, the incessant repairs to a costly and delicate instrument and disappointment and delay attending miss-fires will be avoided, and the drillers will be detained from their labor at each discharge for a less period of time.

“The order of charging and firing is as follows: When the drill holes have been completed, (say every four hours) signal is made, for the cartridges which are only then taken into the Tunnel, (the Nitro-Glycerin in its containing cartridge in one vessel, the exploders, with priming and connecting wires attached, in another separate vessel.) On arrival at the heading, the miners are dismissed to a safe distance, the drill holes are then gauged, to be assured they will receive the cartridges; now, and for the first time the exploders are attached to the Nitro-Glycerin cartridges, and immediately passed into the drill holes, these latter are plugged with a bung, perforated to allow the delicate connecting wires to pass, (thus avoiding cutting the insulation against the rock, and confining the flame;) connection is made beginning with the return wire to the cartridges consecutively, and on to the conducting wire. The operator now retires from the heading some 300 feet towards the shaft where a simple but important apparatus, or break is arranged; he then and there connects his return wire and his conducting wire to two similar wires that lead to the electrical discharge, which duty is performed in the dry, warm room before referred to, and the explosions take place instantaneously.

The above modification is a necessity to avoid the damaging influence of the moisture in the Tunnel, so disturbing in its effect on the machine. I have only to add, that we have under-way apparatus for coating and re-covering damaged insulated wires, an improvement to insure perfect explosion of the Nitro-Glycerin; the manufacture of Abel’s priming for fuse, the formula having been published by the inventor; matters of comparatively minor importance, but where so many blasts are daily occurring, involving considerable saving in cost and express charges, and securing a better article when made by the individual for his own actual use, than when made simply for sale, all tending to greater safety and certainty in firing the blasts, ameliorations that have already been submitted to and approved by your engineer in charge, who will doubtless speedily report the actual results of blasting operations.

Respectfully,

Geo. M. Mowbray, Operative Chemist.

The following letter from the Engineer in charge to the Commissioners, is interesting, as showing that the Nitro-Glycerin we had made, was superior, and possessed far more valuable properties, than that which had been imported from Hamburg:

North Adams, Feb. 18, 1868.

To the Commissioners of the Troy and Greenfield Railroad and Hoosac Tunnel

Gentlemen:—I have to report that yesterday 4 p. m., we exploded eleven cartridges of Nitro-Glycerin in charges of 1-2 lb. each, in open holes without tamping, with entire success. This experiment was made in the East heading of West Shaft. On approaching the heading, the absence of foul gases and smoke was remarkable, the mass of broken rock lay close to the heading, and there was no appearance of any rock thrown to any distance from the heading. Inquiring of the miners if they experienced any headache, elicited the remark they noticed a pleasant smell, but nothing further. This settles the question of its applicability in a close tunnel. I attribute this freedom from the foul gases which we noticed in our experiments a year since, to the evident purity of this Nitro-Glycerin; it differs greatly from all descriptions of the article, and in appearance from that we imported, being a liquid colorless as water, and free from smell or bubbles. That which we imported was a thick, yellow liquid, quite different in appearance from this. I have requested Mr. Mowbray, who manufactures the Nitro-Glycerin, to take charge of the blasting, and informed him that the Commissioners wish him to assume the responsibility of using the Nitro-Glycerin until further orders, or at least until the system of firing is thoroughly organized among the employees.

I enclose his reply, and approve his suggestions, subject to your instructions.

I am very truly yours,

W. P. Granger, Engineer in charge.

The Commissioners for the year 1868, report as follows:

During the Summer, Glycerin of a very good quality has been manufactured at this point, under the direction of Mr. Mowbray, and has been used for several months in blasting in the tunnel east of the West Shaft. No accident has attended its use. And while its effect in the heading did not meet the expectations of the Commissioners, the result of its operation in the bench below the heading, justifies the belief that with due provision for its economic use, and essential care and attention paid upon its management, it will prove an effective agent in the prosecution of this enterprise.

The Superintending Engineer, Benj. D. Frost, Esq., reports as follows: “The following is a statement of monthly progress.

	Length driven.	Total distance from W. Shaft.
In November,	1867,		33 feet,	1272 feet.
December,	1867,		22 feet,	1294 feet.
January,	1868,		33 feet,	1327 feet.
February,	1868,		35 feet,	1362 feet.
March,	1868,		34 feet,	1396 feet.
April,	1868,		24 feet,	1420 feet.
May,	1868,		26 feet,	1446 feet.
June,	1868,	[3]	21 feet,	1467 feet.
July,	1868,	(Nitro-Glycerin used)	47 feet,	1514 feet.
August,	1868,	“	44 feet,	1558 feet.
September,	1868,	“[4]	51 feet,	1609 feet.

“But for the improved methods of working introduced, the advance would have been much less satisfactory than that we are enabled to exhibit above.

“Concerning the employment of Nitro-Glycerin and machine drilling at West Shaft, it is hardly necessary to remark that many difficulties are to be encountered in the training of men to a new service and in successfully employing a new description of fuse and explosive. Some remarks upon our experience in blasting with this compound, will be found in a subsequent portion of this report. Continuous use of machine drills was commenced at the West Shaft in the latter part of June, and of Nitro-Glycerin as an explosive in the month of August. Some delays were necessarily experienced at first, but greatly improved progress was shortly attained. Some previous trials of machine drilling had been made earlier in the present year, but without continuous progress, upon which satisfactory estimates of success might be based. The last workings made, including the month of September, up to the time of suspension, about five-sixths of a working month, attained a linear progress of 51 feet, with six drills only. The machinery provided at West Shaft is only sufficient to supply the pneumatic power for the ordinary working of the above number, to which accordingly we have been necessarily confined.

The two drill carriages employed are larger than those at East End, and are intended to carry five drills each—in all, ten drills working at the breast of the heading. Assuming, as we may safely, that the rate of progress is proportional to the number of drills employed, ten drills would advance 100 feet per month; and with full power provided and further experience to be acquired by the workmen, this and even greater average rates of monthly progress can be made and maintained.

These headings are run at top, i.e., above the excavations hereafter to be made, and of such height, and top outline as to correspond with the roof of the completed tunnel.

Amounts of progress upon this section of the work during present and preceding year are exhibited in the following comparative table:—

West Shaft	Heading and Adit.	Enlargement.
Section.	Linear Feet.	Cubic Yards.	Linear Feet.	Cubic Yards.
Year Ending
November 1, 1867	543	2349	161	2100
November 1, 1868	1280	4696	82	488

The limited employment of Nitro-Glycerin made previous to August 1st, had been directed to excavations of enlargement, which very nearly resemble open cut work. The experience of the two months, August and September, is all we have that throws direct light upon its value in mining operations, using this phrase in its more limited sense, as applied to advance of heading only. The varying hardness and tenacity of rock and other attendant conditions, make material variations in the progress of separate days or weeks, even in the same drift and with the same means and appliances of working.

For the reasons thus stated, actual records of advance without full knowledge and discussion of all attendant circumstances, and more especially when confined to short periods, must not be held conclusive in regard to the measure of advantage to be derived from its use. We cannot claim that in this short time, full knowledge as to its best possible application has been obtained. Its superiority over the powder ordinarily used in blasting, as demonstrated by our experience may be briefly expressed in the following items:

“1. Less number of holes drilled in proportion to area of face carried forward. Estimated saving 33 per cent.

“2. Greater depth of holes permissable. Average depth of Nitro-Glycerin, 42 inches; for blasting powder, 30 inches.

“3. More complete avail of the full depth of hole drilled. The greatly superior explosive power of the Nitro-Glycerin rarely fails to take out the rock to the full depth of the hole. Powder often comes short of this, and by reason of this loss of useful effect, a large percentage of additional drilling becomes necessary.

“In all the foregoing comparison, I assume it to be understood that simultaneous blasting by electric battery is employed. The great economy of force secured thereby, whenever hard rock may be encountered, is admitted by all conversant with the matter, and since the early part of the Summer, I have continuously employed it in both the headings advancing into the mountain.

“It is hoped and expected that further experience will demonstrate an increase in each of the several items of advantage resulting from Glycerin blasting; and it is only claimed that the best use was made of the short term of experiment afforded, and the most faithful and diligent effort was put forth to attain the best results and greatest benefit therefrom to the Commonwealth.

“It was a source of great disappointment that Professor Mowbray should have been unable sooner to provide a continuous supply of the explosive, and in view of the fact that a small quantity was furnished earlier in the year, it is appropriate to make mention of the obstacles which for a time delayed its further manufacture. The first lot produced was made with imported acids, reaching the actual standard of purity represented. In providing for more extended operations, acids were ordered of American works of the same expressed standard, but these when received, were found so far below requirement, that a separate process of purification became necessary. For this process, retorts of a special pattern not to be procured in market, had to be manufactured, and separate works erected, and in the processes, necessity for which was not foreseen, much delay was unavoidably encountered. I have been fully satisfied throughout of Professor Mowbray’s earnest desire fully to meet the expectations of the Commissioners and of the public, and deem it proper to make this general statement of the more important circumstances, unanticipated, and therefore beyond his control, which disappointed his purpose.”

I have been thus explicit in narrating the various details connected with the introduction of Nitro-Glycerin at the Hoosac Tunnel, in order that full justice might be done to the gentlemen whose enterprise and authority were necessary to bear up against the prejudices which the three explosions hereinbefore referred to had caused on the public mind. It is now five years since I commenced, and have with slight intermission, continued, to manufacture this explosive, and during this whole period but two accidents have occurred at my works. The first occurred on the 23rd of December, 1870, to my foreman, who I surmised, in the absence of proof, in removing the clinkers from the heater, may have thrown a red hot coal on to the inflammable floor boards of the magazine, moistened with Nitro-Glycerin spilt during three years use, whilst adding fuel to the parlor stove which warmed it. It is a poor consolation that Mr. Velsor, the foreman, who had been engaged with me during the greater part of the past ten years, had finished his day’s work and was using the magazine for a bath house, probably on account of its seclusion. Universally respected, thoroughly acquainted with the properties of Nitro-Glycerin, careful and untiring, cool, courageous, and without bravado, his superintendence of the factory where thousands of pounds of this explosive were being handled, and in the course of distribution to different points of the United States, was steadily and quietly overcoming the dread of this powerful blasting agent; accompanying me and aiding in the most difficult operations of submarine blasting, in every case without a shadow of accident, lead to one conclusion, that some slip of the hand, failure of a muscle, started a flame, which in a magazine crowded with receptacles for Nitro-Glycerin no human power could arrest, but which I am satisfied, his courageous sense of duty led him to attempt, and thereby sacrificed his valuable life.

The new magazine had hardly been completed, and stored with Nitro-Glycerin, when on Sunday morning, 6:30 o’clock, March 12, ’71, the neighborhood was startled by another explosion of sixteen hundred pounds of Nitro-Glycerin. The cause of this last explosion, was continuous overheating of the magazine. Work at the factory had been suspended for a week, the heating arrangement was now effected by steam, in order to avoid a possibility of actual fire, the weather for several days had been close and muggy,—some parties who had visited the magazine remarked to me afterwards, they had noticed a hot, close air, similar to that experienced on entering the drying room of a print factory, whilst the watchman confessed he had neglected to examine the thermometer, made up his fire under the boiler, and gone to bed. I had been summoned during the previous week to Washington, taken down with sickness and unable to return home,—the new foreman having been closely at work without any Christmas vacation, owing to the previous accident, availed himself with my permission, (during the suspension of work at the factory) to visit New York. Fortunately this accident involved no damage to life or limb, whilst a very instructive lesson was taught in the following circumstance: within twelve feet of the magazine was a shed, 16×8 containing twelve 50 lb. cans of congealed Nitro-Glycerin ready for shipment. This shed was utterly destroyed, the floor blasted to splinters, the joists rent to fragments, the cans of congealed Nitro-Glycerin driven into the ground, the tin of which they were composed perforated, contorted, battered, and portions of tin and Nitro-Glycerin sliced off but not exploded. Now, this fact proves one of two things, either that the Tri-Nitro-Glycerin made by the Mowbray process, differs from the German Nitro-Glycerin in its properties, or the statements printed in the foreign journals as quoted again and again that Nitro-Glycerin when congealed is more dangerous than when in a fluid state, are erroneous.

The following incident is, to say the least, instructive: during the severe winter of 1867 and 1868, the Deerfield dam became obstructed with ice, and it was important that it should be cleared out without delay; W. P. Granger, Esq., engineer in charge, determined to attempt its removal by a blast of Nitro-Glycerin. In order to appreciate the following details, it must be borne in mind that the current literature of this explosive distinctly asserted that when congealed, the slightest touch or jar was sufficient to explode Nitro-Glycerin. Mr. Granger desired me to prepare for him, ten cartridges, and as he had to carry them in his sleigh from the West end of the Tunnel to the East end or Deerfield dam, a distance of nine miles over the mountain, he requested them to be packed in such a way that they would not be affected by the inclement weather. I therefore caused the Nitro-Glycerin to be warmed up to 90°, warmed the cartridges, and after charging them, packed them in a box with sawdust that had been heated to the same temperature; the box was tied to the back of the sleigh, with a buffalo robe thrown over it; in floundering across the divide where banks, road, hedge and water courses were indistinguishable beneath the drifted snow; horse, sleigh and driver were upset, the box of cartridges got loose, and were spread indiscriminately over the snow; after rectifying this mishap, picking up the various contents of sleigh, and getting ready to start again, it occurred to Mr. Granger to examine his cartridges; his feelings may be imagined when he discovered the Nitro-Glycerin frozen solid; to have left them behind and proceeded to the dam where miners, engineers and laborers were waiting to use this then much dreaded explosive, would never do, so accepting the situation he replaced them in the case, and laying it between his feet proceeded on his way, thinking a heap but saying nothing; arrived, he forthwith attached fuse, exploder, powder and some gun cotton, and inserted the cartridge in the ice; lighting the fuse he retired to a proper distance to watch the explosion; presently a sharp crack indicated that the fuse had done its work, and on proceeding to the hole drilled in the ice, it was found that fragments of the copper cap were imbedded in the solid cylinder of congealed Nitro-Glycerin, which was driven through and out of the tin cartridge into the anchor ice beneath, but not exploded. A second attempt was attended with like results. Foiled in attempting to explode the frozen Nitro-Glycerin, Mr. Granger thawed the contents of another cartridge, attached the fuse and exploder as before; this time the explosion was entirely successful. From that day I have never transported Nitro-Glycerin except in a frozen condition, and to that lesson are we indebted for the safe transmission of more than one hundred and fifty thousand pounds of this explosive, over the roughest roads of New Hampshire, Vermont, Massachusetts, New York, and the coal and oil regions of Pennsylvania, in spring wagons with our own teams.