The Mechanical Branch of the Association of Li" censed Automobile Manufacturers has just issued to its members a report on materials which have been tested and experimented upon at the Hartford laboratory for the past year, also the complete specifi cations for various kinds of steel which have been found. to be most desirable for specific parts of automobile con" struction. During the year scores of samples of spe" cial steel of unusually high grade have been tested. They were tested in the

more »

... ural condition, as received Uorh th,e steel works, tested annealed for heat treat" mEmt, and tested to' ascertain the toughest possible condition combined with strength. Some of the steels experimented with were silicon and manganese with chromium, vanadium, silico"manganese, chrome nickel, and n' ickel. Vanadium, which is just becoming known to some manufacturers, has been under experiment for nearly a year at the Hartford laboratory. Many of the mem" bers of the Association of Licensed Automobile Manu" fadurers have been using vanadium steels for over a year, but only since the elaborate tests which have been made by the Association's metallurgical force has the recommendation and adoption been universal with the Association members. The results of the ex" periments have proven the desirability of vanadium steels for special parts of automobile construction. It is a most elusive element and its introduction to the basic material must be carefully made. It seems to act as a cleanser if judiciously used, and eliminates many elements which otherwise would be a detri" ment to the steel. J. Kent Smith, the English metal" lurgist and exponent of vanadium, in his address to the members of the Mechanical Branch, stated authori" tatively that "vanadium steel was the fi nest steel for mechanically"moving machines." The elements of vanadium are to be found in many substances, but only in microscopic form. Swedish iron contains a small quantity of this valuable material. The pres" ence of vanadium in steels has a tendency to add longer life, strength, and durability. It is easily welded, it is superior in rigidity, and extremely easy to machine. Its elastic limit under all conditions is extremely high as compared with the tensile strength, for use in gears, frames, axles, crankshafts, and pro" pelling shafts. Vanadium steel is considered to be more serviceable than any other metal' known. Specifi cations for the treatment of metals for A. L. A. M. screw material, cylinder iron, steel castings, and nickel castings were issued, with directions for ob" taining the maximum results in their use. The visit of the members of the Mechanical Branch, iI),. a body, to the Bethlehem Steel. Works, as the lat" ter's guests, was accompanied by some interesting re" suits. The._ Branch spent the entire day minutely in specting the methods employed by the Bethlehem Steel Company in the manufacture of special grades of steel. The willingness of the large steel companies to co-operate with. the Association in the manufacture of the highest grade of material is, in a measure, respon" sible for the superior grade o� steel found in the licensed cars. Thorough investigation by the test committee brought out the fact that not only was there consid" erable variance between the practice of various manu" facturers in the use of taps and drills, but even the screw manufacturers were at variance in their own establishments. A standard drill size was suggested and adopted by the members of the Branch and the outside makers of drills and taps. The adoption of a uniform magneto base was thproughly recommended, especially when it is known that many new magnetos are to be placed on the market. The tendency of the makers for their 1908 models will be the use of mag" netos. These will have a standard base, so that option on magnetos can be given without reconstruction of base standards. A new department of the Branch which will be a source of benefit to each engineer, and in fact to the whole engineering world, will be the Mechanical Branch Technical Library, under the directorship of Coker F. Clarkson, secretary. The library, to be formed at the Association rooms, will consist of not only all the necessary books and papers on engineering subjects of pertinent interest, but an accumulative in� dexed library will be kept on all topical engineering subjects. Results of all experiments and researches in metals, oilS,. tires, fuels, etc., will be digested and put in concrete form for distribution to the members of the Licensed Association. Experiments, tests, and formulffi emanating from the Association laboratory at Hartford and from the laboratories of all the licensed members will be chronologically and specifi cally tabu lated. A digest of popular and scientifi c subjects ap pearing in current periodicals will be made, and metal lurgical information collected from all sileel manufac" turers and producers. In this way the practical knowl edge of the manufacturer and the theoretical research Work of the scientist are made available. In a stereoscopic view two photographs, taken from two points not very far distant from one another, give the effect of relief when viewed through the instru ment. It is commonly believed that this fact proves the necessity of binocular vision to obtain a relief ef fect. The following experiment shows that the same perception can be had with the use of one eye only and with a flat drawing, if the eye is deceived by some arti fice which it is not educated to recognize as such. Take a piece of pasteboard, and with a pin make a hole in it. Bring the pinhole quite close to the eye, and through it look at the accompanying fi gure. The figure should be in full light, and at a distance from the pinhole not over one inch. Under ordinary circum stances, every line would be blurred with the fi gure so uncomforta bly near the eye; but the pinhole acts as a diaphragm, which decreases several of the defects of a short-focus lens, -and the fi gure will remain distinct not only distinct, but also changed in appearance. The central white disk will seem to bulge out of the black fi eld as if it were a convex hemisphere. The percep" tion of relief in that case is immediate, and as strong as it could be obtained with the stereoscope. The illusion is partly the result of the abnormal curvature of the focal surface, the crystalline lens of the eye acting as a very short-focus lens in such a case. The lines drawn on the white disk and on the black fi eld help to deceive the eye. Their crowding together near the edges of the disk causes them to resemble great circles drawn upon a sphere. More" over, the eye is not free from distortion. If a few parallel lines running close together are looked at through a pinhole at a very small distance, they ap" pear as if they were bent inward on the margin of the image. On the white disk the lines have been curved the way distortion would bend straight lines if they were brought close to the eye. On the black field white lines have been drawn so as to appear nearly straight in spite of the barrel-shaped distortion, which is the resul t of the pOSition of the diapht: agm before the eye w hen the cryst a II i n e lens assumes con v e xi t y.