DISCUSSION (Continued).
NEWPORT BRANCH.
February 1, 1888.
Lieutenant Karl Rohrer, U.S.N., in the Chair.
The Chairman.—In introducing the lecturer of the evening I may, perhaps, be pardoned a word or two of explanation. To most of us this explanation is entirely unnecessary, but that we may all enjoy an equality of acquaintance, I beg to remind you that he is one of the inventors of the electric furnace, and that, in conjunction with his brother and Professor Mabery, he has brought within economic reach a metal possessing such extraordinary qualities that it has been spoken of as the metal of the future. Possessing great lightness, great tenacity, and great resistance to corrosion, its application to many phases of construction is but a question of time. Others before him have produced the metal aluminum, but on the laboratory scale and in quantities so small as to be practically restricted to museums. He, however, offers it and its alloys to the engineering world in commercial quantities, at a price which permits its employment in structures where its particular qualities are demanded, and I understand that soon it will become still cheaper.
It is hardly necessary to say that the introduction of this metal into the list of those available is a notable event in the history of metallurgy. To us of the naval service this event is of peculiar significance, as the lecturer proposes the employment of aluminum bronze as a substitute for steel in modern guns.
This project was first laid before our Institute in October last, and the discussion which ensued created such interest at home and abroad that further light on the metal itself, as well as upon its adaptability to ordnance, was thought desirable. In consequence the lecturer has been kind enough to appear again before the Institute, with new facts and new specimens of whose characteristics he himself will speak.
Gentlemen, I have the honor to present to you Mr. Alfred H. Cowles.
Mr. Alfred H. Cowles.—Mr. Chairman and Gentlemen:—There are so many present who can more ably and impartially criticize the papers presented at the Annapolis meeting than my brother or myself, that I will not undertake to speak further in regard to them. We endeavored to make it clear that our position was not that of attacking the present method of making guns of steel as recommended by our government ordnance officers. We consider, on the contrary, that the all steel “built-up” gun is the product of the best known practice of the present day. We are presenting our subject to you, not as gun makers, but as the producers of a new class of alloys having combinations of physical properties which we believe render them superior to steel in the fabrication of guns, inasmuch as they can be perfectly cast to the form of a completed gun. Were we gun makers, we would have first produced a gun and pointed out its merits as a basis for discussion. But as producers of these new metals, we desire that the ordnance officers and the gun makers may become familiar with their properties, learn wherein they are applicable to their work; and we hope that as an outgrowth of this discussion a number of experimental guns will be produced in Europe and in this country during the ensuing year.
Through the courtesy of Engineer-in-Chief Melville of the Navy, I am enabled to give you the following report of Chief Engineer W. H. Harris upon some tests of extraordinarily large bars of metal that were recently tested at the Watertown laboratory to determine the value of the alloys as propeller blade metals It is generally conceded that small bars of metal are stronger and more ductile than large bars of the same metal.
The data given by authorities on this point is very meager. Hodgkinson found that in cast-iron bars of one, two and three-inch cross section of area this loss of strength was very great; the relative tenacities were as 100, 80 and 70. James, in repeating the experiment, obtained the figures of 100, 66 and 60. Captain Eadsf broke a life-size forged steel member of the St. Louis bridge, and obtained a tensile strength of only about one third that shown by small bars cut from the same piece. The small bars showed great ductility, which failed to develop in breaking the life-sized member.
Navy Department,
Bureau of Steam Engineering,
Washington, December 20, 1887.
Sir:—In obedience to orders of the 22d ultimo, I have visited Watertown, Mass., and Lockport, N. Y., to witness experiments at the former place upon specimens of aluminum bronze and brass submitted for tensile tests by the Cowles Electric Smelting and Aluminum Company, of Lockport, N. Y., which place I visited after the tests at Watertown were completed.
In competition with the bronze specimens furnished by the above company, the Bureau directed that six specimens of tin bronze usually used for propeller castings in the U. S. naval service, be tested under like conditions.
All specimens tested were 15 inches in length between reference marks, and if finished all over, were 1 7/8 inches diameter; those which were left as taken from the sand were slightly in excess of this diameter, 1.93 inches being the greatest diameter recorded.
A tabulated statement of the results of the tests is appended to this report. A comparison can be made between the aluminum bronze castings marked D, and the tin bronze marked 4, 5 and 6, all these specimens being left as they came from the sand.
The average of the three tin bronze specimens being: T, S. 22,400; E. L. 13,000; elongation in 15 inches, percentage 3.34; reduction of area 7.98 per cent.
Comparing the specimens marked 9, 10 and 13 D with the above: 9-D shows 53,000 — 22,400 =130,600 pounds:= 136 per cent greater tensile strength. 19,000— 13,000 = 6,000 pounds = 46 per cent greater elastic limit. 6.2 — 3.34 =2.86 = 85 per cent greater elongation. 15.5 — 7.981= 7.52 =194 per cent greater reduction of area. 10-D shows 69.930 — 22,400 =47,530 pounds = 212 per cent greater tensile strength. 33,000 — 13,000 = 20,000 pounds 1=153 per cent greater elastic limit. 3.34 — 1.33 = 2.01 = 60 per cent less elongation. 7.98 — 3.3 = 4.68= 59 per cent less reduction of area. 13-D shows 46,500—22,400 = 24,100 = 107 per cent greater tensile strength. 17,000— 13,000 = 4,000 = 30 per cent greater elastic limit. 7.8 —3.34=: 4.46 = 133 per cent greater elongation. 19.6 — 7.98 =11.62=1145 per cent greater reduction of area.
All of the above aluminum bronzes can be worked hot or cold, but no experiments have been made, to my knowledge, to determine their strengths after such working.
It makes sound and sharp castings; its greater tensile strength allows the use of thinner and consequently lighter blades for propellers, and its great ductility allows of its being bent nearly at right angles without showing cracks or flaws.
I have no knowledge of any alloy of copper which as a casting combines the qualities which this material possesses.
At the works at Lockport, N. Y., I found that 30 tons of the high grade aluminum bronze or 90 tons of aluminum brass per month is the present capacity of the works; but in the designing of the plant, arrangements were made for an increase of 100 per cent in product, which the manager of the works, Mr. Dudley Baldwin, Jr., states can be effected in ninety days.
Very respectfully,
(Signed) Wm. H. Harris,
Chief Engineer, U.S.N.
Engineer-in-Chief Geo. W. Melville, U.S.N.,
Chief of Bureau of Steam Engineering,
Navy Department, Washington, D. C.
The following table shows the results of tests on the hardness of the large bars:
Aluminum bronze or brass— | ||
Mark | Hardness of Head | Hardness of Stem |
1C | 9.39 | 13.85 |
7C | 14.12 | 14.26 |
9C | 11.18 | 13.59 |
11C | 14.69 | 10.60 |
10D | 17.08 | 16.07 |
Navy Yard Bronze— | ||
No. 1 | 3.33 | 3.33 |
No. 5 | 3.67 | 6.56 |
The bars furnished by the Government and marked “navy bronze” were carefully cast at the New York Navy Yard and under the inspection of an officer detailed for that purpose, and were exceedingly fine castings. You will notice that they are of the composition of ordinary gun bronze.
Bars of this metal of 79/100 inch diameter (such as are usually tested) would have about 39,000 pounds tensile strength to the square inch, 13,200 pounds elastic limit, and from 25 to 33 per cent elongation, thus showing a falling off in these large bars of about 45 per centum in strength and a very great lessening in their elongation. The aluminum alloys likewise show a lower strength and ductility than was obtained from bars one third of an inch in diameter that were tested in the works of the Cowles Electric Smelting and Aluminum Company at the time the large bars were cast; these small bars ranged from 12 to 35 per cent higher in strength and much higher in ductility than was developed by the Watertown tests.
At the Annapolis meeting it was claimed that the present form of “built-up” steel guns had all the strength needed. I merely call your attention to the fact that since the date of that meeting we have learned of the bursting of the De Bange 14-inch steel gun at Calais, France. The bursting in this case was not the blowing off of the unhooped muzzle, but was just forward of the trunnions and through the body of the gun.
In pointing out the defects in the present method of gun building, it is our endeavor to ascertain the cause of such accidents as this and learn if the “built-up” steel guns cannot be improved upon, and their defects removed, by the substitution of a metal whose physical properties surpass those of steel, and that may be cast as a whole. In doing this, it is not to be denied that the present “built-up” steel gun is superior to anything heretofore produced.
In Notes on the Construction of Ordnance No. 41, issued last April by the War Department, we find that Mr. J. E. Howard, of the Watertown testing laboratory, by his ingenious and scientific methods has made two valuable discoveries which bear directly upon the present method of fabricating “built-up” guns. He showed (page 19) that compressive and tensile tensions begin to relieve themselves when steel is subjected to 42S degrees Fahrenheit. The effect of long-continued heating at lower temperatures than this, or often repeated heating such as the bore of a gun is subjected to, has never, to my knowledge, been definitely determined, yet rumors in old treatises on ordnance have it that the internal strains set up in casting cast-iron guns relieve themselves with the varying heat of winter and summer. It is for those who use the guns to state whether the bore is ever subjected to this temperature.
Mr. Howard has further demonstrated (pages 6 and 31) that oil tempering a ring of gun steel throws the entire surface immersed into an initial state of compression, and the inner portions of the metal into a reverse state of initial tension. In a case where the bore of a tube was quenched while at a bright red heat with water, a range of tensions and compressions from the outside surface to the inner surface of 109,874 pounds to the square inch were found to exist. The presence of these initial tensions in oil-tempered steel rings shows that a gun built of an aggregation of such rings cannot have the nicely calculated variation of compressions and tensions from the centre outward that is sought, since the parts before they are assembled have each within themselves initial strains. The initial strains within each ring may be altered by the shrinkage process, but they only exist in another form to destroy the uniformity of the result desired.
It seems strange that the molecules in one part of a mass of steel such as that here referred to should have a repellent action for each other up to their elastic limit, while in another part of the same mass they should have a greater affinity and endeavor to pull themselves closer together with no other apparent cause than having been cooled quicker or slower by quenching; and further, that the strength and elastic limit of the metal should thereby be raised.
One is led to regret that more of this exact work is not done, and that all the physical properties of many of the bars of metal tested by our Government and the exact chemical composition of the same are not determined. By all the physical properties I mean those that are now ordinarily determined so nicely, together with the specific gravity, the specific heat, electrical conductivity, the coefficient of expansion, and thermal conductivity. Such work would soon accumulate a mass of data that would give us a deeper insight into molecular physics, might enable us to tell the physical properties of a combination of metals from those of the elements, and would certainly greatly aid the metallurgist in producing specified results.
I thank you, gentlemen, for the many courtesies extended to me and the interest thus far manifested in the subject I have had the good fortune to present to you.
To the Members of the U. S. Naval Institute.
Gentlemen:—I thank you for the honor you have paid me in sending me a copy of the very interesting discourse that Mr. Alfred Cowles delivered before you on the 27th of last October at Annapolis.
On this subject I beg your permission to say a few words as to the history of aluminum bronze and its applications, and I will close with some observations on the special question which is made the object of your meeting at Newport.
I am much interested in the subject of the uses of aluminum bronze, a subject with which I have been occupied for nearly thirty years past. I was sent to England in 1859 by Mr. Sainte Claire Deville to take part in the first manufacture of aluminum bronze at Washington, near Newcastle, in the house of Bell Brothers, under the direction of one of the Bell brothers, a metallurgist well known to you to-day as Sir Lowthian Bell. As far back as 1860 they commenced the manufacture of aluminum and aluminum bronze, and used it for several industrial purposes.
Mr. John Percy, in England, and Mr. Debray, in France, have studied the alloys of aluminum and copper, and have noted some remarkable peculiarities. To Messrs. Paul Morin and Lechatelier is due the credit of having sought out the most various applications and the most precise particulars as to the mode of working aluminum bronze. All experiments in the employment of aluminum bronze at that time were crowned with success as to the material results obtained, but the great cost of the metal (15 francs the kilo) prevented the efforts for popularizing the use of aluminum from bearing fruit.
The bronze aluminum was obtained by adding to melted copper a certain percentage of aluminum, its price depending then on the price of that metal. The method of reducing the aluminum invented by the illustrious Wohler and adopted by Sainte Claire Deville in his remarkable creation of the industrial working of aluminum, could not produce this metal at a sufficiently low price so that its alloys with copper, notwithstanding their remarkable qualities, could enter into the grand industries and be put in competition with ordinary bronzes.
Every kind of work in which the special qualities indicated in aluminum bronze would be required has been undertaken by Paul Morin, from the most delicate objects of the goldsmith's art, secular and religious, to the most diverse pieces of machinery, shaft bearings, slide valves, props of locomotive cabs, etc., etc.—all, even pieces of artillery, have been made and tried by Paul Morin. In fact, early in 1860 a small mountain howitzer in aluminum bronze was cast at the foundry of Nanterre by Paul Morin, and I find in a letter from him, dated April 6, 1860, the following passage: “The cannon has been cast. Before delivering it at the artillery depot where it is going to be tried we have polished it and have cut off the sinking head. The metal appears very perfect and is of an excellent quality notwithstanding the numerous remeltings previously undergone.”
It would be very interesting to know the conclusions of the Board of Artillery after the experiments to which the cannon was submitted, but the report has been kept secret, and we have only been told that the results obtained after extreme trial were very interesting and satisfactory.
Why then, you ask, have they not pursued the experiments, since such good results were obtained? I cannot say, but I think that the high price of aluminum bronze was one of the principal reasons that prevented experiments with pieces of a greater calibre; they were without doubt afraid to spend too much in experimenting with a metal all the qualities of which were not yet well known at that time. In fact, one was not then very certain that these aluminum bronzes would always present the same qualities whilst working under the same conditions. There were often sensible differences, due to hammering or rolling—sometimes they blamed the copper, sometimes the aluminum for being the cause of the bad results obtained. It was only after numerous experiments made at the laboratory of the foundry for aluminum at Washington, and by Mr. Paul Morin at the foundry of Nanterre, that the conviction was arrived at that the quality of the copper played a preponderating part, and that if it was desired to obtain to a certainty aluminum bronzes of good quality, it was necessary to employ copper from Lake Superior exclusively, or the pure copper furnished from galvanic depots. In fact, many manufacturers have found that the trial of a copper for making aluminum bronze was the best proof of the copper. If the bronze obtained was of good quality, they were then sure that the copper tried could be employed and, notwithstanding what was done to it, it would give good results. These are, I think, the principal reasons why the trials of aluminum were not pursued in the construction of cannon. It is also necessary to add that at this epoch commenced the era of iron and steel for weapons of war.
I like to think that, after having waited for more than a quarter of a century, I shall see the era of aluminum bronze arise; regretting only that Sainte Claire Deville, Paul Morin, and Lechatelier are no longer here to see the realization of their works and hopes.
I have on this account read with great interest the remarkable work of Mr. Alfred Cowles on the employment of aluminum bronze at 10 per cent for the pieces of artillery of large calibre, and on the superior results that they have a right to expect in regard to the endurance of the pieces, their resistance, and the economy of their production. My studies do not permit me to discuss with sufficient authority the technical questions arising as to the employment for great guns of aluminum bronze. I will ask, however, to call your attention to the homogeneity of aluminum bronze, which should not be considered as an alloy, but as a well known veritable combination. The enormous quantity of heat which is disengaged when they add the aluminum to the copper proves it superabundantly.
Whatever be the dimensions of the cast pieces, they can be more or less successful as regards the casting; but as for the quality of the metal, it is the same in whatever part of the mass it may be—this is an important point.
With aluminum bronze there is no fear of the liquation that takes place in ordinary cannon bronze, and thus the sinking head can be much smaller. In making comparisons with iron and steel it must not be forgotten that aluminum bronze is a veritable combination, a metal of a composition better defined and infinitely more stable than even steel itself, completely free from the molecular changes which so often alter pieces of steel in their primitive qualities after having accomplished a certain work. This tendency to crystallization that steel subjected to repeated shocks possesses, and which renders ruptures possible and always to be feared, will be much less to be dreaded with aluminum bronze.
I recall having used some special pieces of 10 per cent aluminum bronze for a nail-making machine; these pieces received several hundred blows a minute, and have stood the hammering admirably, whilst the same pieces in a special quality of steel, employed before these, were rendered useless in five or six days' work.
The difference in price can no longer be quoted in favor of steel, since, when one recognizes the necessity of abandoning cast-steel guns and the making of guns of many pieces, in this instance the first cost of the metal employed is nothing in comparison with that of the metal worked and finished. With aluminum bronze they will have all the qualities of the built-up gun without having excessive hand-work; moreover, in case of failure the material employed is not lost and can be utilized for a new casting. Those who have worked much in aluminum bronze know that successive castings, far from injuring, improve its qualities.
I can then only confirm the opinion enunciated by Mr. Alfred Cowles, knowing that, if it has been recognized that a “built-up gun” in steel is preferable to a cast-steel gun or an ordinary bronze gun, it does not follow that the built-up gun must necessarily be superior to the aluminum bronze gun cast and treated under conditions which give to the metal its maximum resistance and elasticity.
With Mr. Alfred Cowles, I should say that a cast gun in aluminum bronze can present all the advantages of a built-up gun in steel without its disadvantages. Already there is much interest manifested in France over the question of aluminum bronze since the electric furnace of Messrs. Cowles Brothers permits the production of it at a cheap rate un-hoped for even by the practical men interested in aluminum.
The scientific men who are occupied in the construction of pieces of artillery will be the first to employ aluminum bronze as soon as the production of the metal by the Cowles process is an accomplished fact in our country; the customs rates are so high at present as almost to amount to prohibition (5 francs the kilo for aluminum bronze).
In the near future it will not only be for weapons of war that aluminum bronze will present great advantages. The constructors of machines in general, amongst others those requiring great speed, such as for running dynamos directly, will find in the employment of aluminum bronze, on account of its tenacity, its coefficient of elasticity, and its feeble density, the means of solving some mechanical problems up to the present time remaining unsolved.
In summing up that which concerns the application of aluminum bronze to heavy guns, permit me, gentlemen, to repeat to you what my dear master and friend Henri Sainte Claire Deville said: “II ne faut pas faire d'hypothese, quand on pent faire l'experience”; or in other words, make a gun in aluminum bronze and try it. I beg you, gentlemen, to excuse this letter, which will not shed much light on the subject; but I desire only that my experience, feeble though it may be, may sustain the proposed plans of application by Messrs. Cowles of one of the products of their remarkable discovery, “the electric metallurgy,” which opens a new era for the industries and activity of nations. Accept, gentlemen, the expression of my most sincere respect.
Henri Brivet, Civil Engineer,
Late director of the Altimimim Foundries at Washington, Eng., and of Salindres, France.
Mr. George Allan, C. E.—I have the honor to thank you for your copy of the paper read by Mr. Alfred H. Cowles before the members of the Institute on the 27th October last, on the subject of aluminum bronze for heavy guns.
In England, the improvement of steel to be used in the manufacture of guns has, in the last year or two particularly, had special attention directed to it, and there can be no doubt that the investigations already made, and which are still going on, will result in the improvement of gun steel as well as in the mode of gun construction. The English Government specification for gun steel has been recently revised, and under the tempered tests there is now required a yielding point not less than 22 tons and not more than 33 tons, and a breaking strain not less than 35 tons and not more than 45 tons per square inch. The influence of determinate quantities of carbon and manganese in the steel has become better known, and it is now expected that the addition of aluminum will give a higher yielding point as well as a higher breaking strain.
Experimentally treated with aluminum, steel has already been produced in England having its yielding point as high as 27 tons and its breaking point 37 tons, with 60 per cent elongation in 2 inches. This is, therefore, a very decided advance. Still, in my judgment, the high qualities developed in the aluminum bronze manufactured by the Cowles Company appear to promise it ere long the first place among metals for the manufacture of guns. Its elastic limit and its breaking strain are each of them about 25 per cent higher than in steel. It casts well, and when hot works splendidly under the hammer. It is perfectly malleable at red heat, and rolls beautifully into plates and sheets at a high heat. With a metal of this character and possessing such properties, I am quite of Mr. Cowles' opinion that a solid gun of aluminum bronze would be decidedly superior to a built-up gun of any other metal.
As the destruction of all guns is chiefly due to excessive erosion, the same would equally apply to those of aluminum bronze; but I am disposed to believe that the unctuous character of the metal and its softening property under tempering, coupled with its known hardness, would ensure a greater immunity from erosion than that which is possessed by steel liners. This, however, is a point easily determined, and if a liner of steel was found to be desirable, that modification would not, in my judgment, militate in the slightest degree against the otherwise solid construction of the gun.
Up to the present time, comparatively little has been known about aluminum bronze as a metal—its price hitherto having been prohibitory to its use—but the Cowles' production of it now on a commercial scale, and at a price that permits of its use in competition with other alloys, has given quite an impetus to its application in every direction in England. I have given attention to it for the past two years, and know of many admirable results obtained by it for important uses, notably the construction of torpedoes in their most important parts, the casting and forging of which has conclusively proven to my mind the perfect suitability of the metal for guns and its capability to work admirably under every operation throughout their construction.
The subject is deserving of the highest consideration of all governments, and coming from your Government—as the metal itself does from your countrymen—the proven success of it for guns would be not the least of the many benefits which your country has already conferred upon the Old World.
James E. Howard, C.E.—In response to your kind invitation to take part in the discussion of Mr. A.H. Cowles' interesting paper on aluminum bronze for heavy guns, I regret that I am in possession of so few data bearing upon the subject.
The Messrs. Cowles have produced some bronzes of great value for many useful purposes, of which it is a pleasure to testify; the fitness, however, of aluminum bronze for the purpose of heavy gun construction appears to be at present somewhat conjectural. The proper metal for this purpose is obviously that which best fulfills all the requirements of the case; therefore to regard aluminum bronze as a suitable metal for gun construction, it must be proven equal or superior to competing metals, and for this there seems to be insufficient evidence.
It will not be understood that in entertaining doubts as to its use in this restricted application, that its merits in other directions are not fully recognized. Any metal which aspires to be used in guns must be a successful competitor with steel, a metal which has a very wide range of useful properties. Steel in its worked condition may have a tensile strength ranging between 50,000 pounds per square inch and upwards of 300,000 pounds per square inch, an elastic limit of from 50 per cent up to nearly 100 per cent of its tensile strength, with hardness and ductility according to its chemical composition and mechanical treatment, a high modulus of elasticity, and comparatively low coefficient of expansion by heat, and be capable of acquiring extraordinary combinations of a number of these physical properties. Where the question of strength is paramount it can hardly be said that steel has a rival. The process of manufacture is well understood, and, subject to present methods of inspection, uncertainties are reduced to a minimum. These remarks refer to steel as it is used in the forgings for the modern type of built-up guns.
There appears to be a lack of knowledge of the strength of aluminum bronze in such sized masses as are required for guns, the tests of the metal having for the most part been from small pieces prepared under conditions dissimilar to those which would probably be experienced in gun construction.
It is not known that difficulties met in the casting of large masses of iron and steel would be less in the case of bronze; whether unsoundness of metal, liquation, alloys of different composition in the same casting, dangerous internal strains, may not continue to be obstacles. The usual benefits of chill-bronze castings may not be realized in large masses.
The methods suggested for the subsequent treatment of bronze castings appear to be also applicable to steel castings, if it were desirable to employ them. It is not known whether it is practicable to obtain a satisfactory system of internal strains during the cooling of a large bronze casting, and experiments show that certain cold treatment, such as mandreling, is confined in its direct effects to a comparatively narrow zone of metal, at least in the case of steel. Meager as our information is concerning the properties of large bronze castings, we are hardly any better prepared to consider the subject of forged and rolled bronze.
From the experiment cited with the hot bronze bar, no superiority over steel is shown, for the latter metal at temperatures from 400° to 600° Fahr. Has been found from 10 to 20 per cent stronger than at atmospheric temperatures.
Commander Goodrich.— I regret extremely that official circumstances prevented my being present at the reading of the paper and taking part in the discussion. It is impossible for me to do full justice to the subject, but as a very imperfect verbal report of the lecture shows that the writer questions the value of oil-tempering and quotes Howard's results, I think it well to point out that the logical conclusion of the argument is entirely against the solid gun, cast on the Rodman principle. It is evidently better to reduce the zones of initial tension by dividing the wall of the gun into concentric rings, thus minimizing the alleged ill effects. This is the practice the world over—a practice based upon experiments on a colossal scale and justified by actual service. We cannot afford to cut adrift from present methods until something better is to be had, something not in nubibus but in re. We want not good guns merely, but the best guns. Our readiness to change existing modes of fabrication is subject to this single condition, that the superiority of the gun, either as to life or cost, is demonstrated beyond cavil. It is for us to abide by definite results and not accept the burden of proving the new inventions to be worthless.
The following letters pertaining to the discussion were received and read by the Secretary:
15 Bedford Place, Russel Square,
London, W. C, November 18, 1887.
Lieutenant Chas. R. Miles,
Secretary U. S. Naval Institute, Annapolis, Md., U.S.A.
Dear Sir:—In accordance with the suggestion contained in letter covering some copies of the paper of Mr. Alfred H. Cowles on “Aluminum Bronze for Heavy Guns,” I have laid the letter before some of the gun men, scientists, and engineers in Europe having special knowledge of the qualities of metal for guns, and presume you will hear from some of them in time for the Newport Branch meeting. In response to the receipt of your letter and Mr. Cowles' paper. Professor James Dewar, F.R.S., Professor of Chemistry, University of Cambridge, writes me as follows, in referring to Mr. Cowles' paper: “So far I regard the results as most important and very promising. I have a little difficulty in expressing any opinion on the matter at the present time, seeing that I may have to investigate the matter with the object of acquiring information for a Government.”
I also enclose herewith a letter from Sir Wm. Thomson, F.R.S., F.G.S., etc., in response to the receipt from me of your letter of invitation and Mr. Cowles' paper—which, from its source, is of interest in the premises.
I am, dear sir, yours faithfully,
Ben. M. Plumb.
The University, Glasgow, November 18, 1887.
Dear Mr. Plumb:—I have read Mr. Cowles' paper with great interest, and it certainly seems to me that the results are very promising in respect to the value of the aluminum alloys made by his electrical process. I do not, however, feel that I have enough of knowledge of the practical questions involved in the application to gun-making to be able to give information or express any opinion on the subject in the adjourned discussion on Mr. Cowles' paper. I am very glad to hear that the factory at Stoke-on-Trent is now nearly ready to commence operations, and shall look forward with much interest to the results.
Yours truly,
William Thomson.
New York Arsenal, Governor's Island,
New York Harbor, January 30, 1888.
Professor C. E. Munroe,
Corresponding Secretary, U. S. Naval Institute, Newport, R. I.
Sir:—As a matter of interest to those who may be present at the meeting of your Institute on the 1st proximo, I send you to-day by mail a vent piece of aluminum bronze that has been used by the Ordnance Department in a 3.2-inch B. L. rifle.
The metal of which this bouching is made was obtained from the Cowles Electric Smelting and Aluminum Company; with it fifty-six (56) rounds were fired, the powder charge weighing 3.75 pounds and the projectile 13 pounds.
The action of the gas in passing through the vent was from front to rear, the cut at the inner orifice being towards the muzzle.
This vent piece is not submitted as an indication of what may be looked for as the action of the powder gas in the bore of a gun of aluminum bronze. It is known that vent bouchings of steel have been found to eat away rapidly, held to be due to the combustion of the metal; still the erosions in the chamber of our steel field gun have not, after 2000 rounds, been sufficient to render the piece unserviceable.
The bouching of aluminum bronze was tried to determine whether that metal might not prove satisfactory as a substitute for copper.
Will you be kind enough to have the vent piece returned to me after the meeting?
Very respectfully, your obedient servant,
A. MORDECAI,
Lieutenant-Colonel, Ordnance Department, U.S. A.