Transcriber’s Notes:
Underscores “_” before and after a word or phrase indicate _italics_
in the original text.
Small capitals have been converted to SOLID capitals.
Illustrations have been moved so they do not break up paragraphs.
Typographical and punctuation errors have been silently corrected.
[Illustration]
[Illustration]
TRI-NITRO-GLYCERIN,
AS APPLIED IN THE
_Hoosac Tunnel, Submarine Blasting,_
ETC., ETC., ETC.
BY
GEO. M. MOWBRAY,
NORTH ADAMS, MASS.
1872.
NORTH ADAMS:
JAMES T. ROBINSON & SON, PRINTERS AND BINDERS,
TRANSCRIPT OFFICE,
Transcript Building, Bank Street.
1872.
Entered according to Act of Congress, in the year 1872,
by GEORGE M. MOWBRAY,
In the Clerk’s Office of the District Court of the
District of Massachusetts.
DEDICATION.
TO WALTER SHANLY, M. P.
Indebted to you for the resources which have enabled me to investigate
the properties of Nitro-Glycerin, and render its manufacture a
commercial success, permit me to dedicate the following pages in token
of my appreciation of the indomitable energy, admirable organization,
integrity of purpose, and engineering talent which have rescued the
Hoosac Tunnel from the mire of politics and rendered it an engineering
success; notwithstanding extraordinary impediments of flood, water
fissures, strikes, jealousy and indifference on the part of those
chiefly interested, that must have been most disheartening to your
mind, and challenged a resolution and resources seldom combined with
the abilities you have shewn in this work. Our relations during the
past three years having been without a ripple, render this, my simple
duty, an agreeable task.
GEO. M. MOWBRAY.
PREFACE.
A paper read by request at the Albany Institute, was the germ of the
following pages; its publication in this form, I considered would
furnish engineers, contractors and railroad directors, who occasionally
apply to me for particulars as to the use of Nitro-Glycerin in the
Hoosac Tunnel, with detailed information impossible to condense in
a business letter. Hurriedly composed during the spare hours of a
manufacture involving grave responsibility, the writer weighted with
the additional task of defeating an attempt to monopolize the use (not
the manufacture) of Nitro-Glycerin throughout the United States, whilst
the subject itself, “Explosives, and firing mines by Electricity,”
constantly demanded experimental research, this work has not the
arrangement nor the completeness I could desire; but the author hopes
it will create a more favorable regard in the public mind, towards the
most powerful blasting agent known, by correcting errors in respect
to its properties, and the casualties attending its use; and assist
miners and contractors to a more intelligent acquaintance with some of
the materials the present advanced state of engineering progress has
brought into practical use.
GEO. M. MOWBRAY.
North Adams, Mass., June 1st, 1872.
CONTENTS.
CHAPTER I.
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.
CHAPTER II.
Submarine Blasting—Erie Harbor—Dimon’s Reef, New
York—Coenties Reef, N. Y.—Oil Wells, Penn.
CHAPTER III.
Nitro-Glycerin considered in its chemical details.
CHAPTER IV.
Electricity in blasting operations.
CHAPTER V.
The Tri-Nitro-Glycerin manufactured at the Hoosac
Tunnel—How Tri-Nitro-Glycerin is made—How
stored—How Gutta-Percha is purified—How the
Exploders are manufactured.
CHAPTER VI.
Explosive mixtures.
CHAPTER VII.
Nitro-Glycerin patents and litigation.
CHAPTER VIII.
Hoosac Tunnel—Drilling by machine—Blasting with
Powder—Nitro-Glycerin.
DIRECTIONS FOR HANDLING AND USING TRI-NITRO-GLYCERIN.
APPENDIX.
A. Memoranda for Contractors.
B. Over-sensitive Exploders.
C. Professor Abel on effects of initial explosion on explosives.
D. Car freighted with 4,800 lbs. Nitro-Glycerin off the track.
E. Accidents at the Hoosac Tunnel.
ILLUSTRATIONS.
PAGE.
I. Vignette.
II. Drilling machine at heading, a photograph taken in Tunnel
by Magnesium light, 7,760 feet from West Portal.
III. Stereoscopic view. Twelve cans after an explosion, 18
IV. “ “ West End, Hoosac Tunnel, 28
V. “ “ East End, Hoosac Tunnel, 39
VI. “ “ Nitro-Glycerin factory, 43
VII. “ “ “ “ interior of
converting room, 46
VIII. “ “ Central shaft, Hoosac Tunnel, 50
IX. Miners ascending “ “ “ “ 58
X. Bursting of can, whilst conveying Nitro-Glycerin,
Hoosac Tunnel, 66
XI. Sinking Central Shaft, Hoosac Tunnel, 74
XII. Profile of the Hoosac Mountain, shewing progress
January 1, 1872, 80
XIII. "Stopeing out" enlargement, East End, 85
XIV. Driving bench work and dumping from heading, West End, 90
(Photographs taken by L. Daft, operating for
Messrs. Thompson & Co., of Albany, the drawings
by Assistant Engineers C. O. Wederkinch and
G. Lunt, the wood-cuts by Andrew & Son, Boston.)
CHAPTER I.
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.
[1] This property distinguishes it from the Mowbray Tri-Nitro-Glycerin,
the latter contracting about one-twelfth of its bulk in congealing;
further, the Nobel patents claim a preparation which congeals at 55°F,
whereas the Mowbray Tri-Nitro-Glycerin congeals at 45°F. No further
evidence is necessary to prove that a real difference of component
parts exists between the two preparations.
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.
[2] This effect has never been produced by the Tri-Nitro-Glycerin
(“Mowbray’s”) and is another and very emphatic proof of the difference
between the two preparations.
“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 Total distance
driven. 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.
[3] Preparing for machine drilling.
[4] September 1, to 24, 5-6 month. Rate 61 feet per month.
“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 | Cubic | Linear | Cubic
| Feet. | Yards. | Feet. | 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.
[Illustration]
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.