Scientific American Supplement, No. 492, June 6, 1885

Excerpt

NEW SPANISH ARTILLERY.

The Spanish Government is now engaged in supplying some of its principal fortifications with heavy guns of the most improved construction. The defenses of Cadiz and Ceuta have been greatly strengthened in this respect. The most recent additions are some very powerful Krupp guns for the fortress of Isabel II., at Mahon.

NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.

We give engravings from photographs, as presented in La Illustracion Española. These guns are breech loaders, of steel, 30½ centimeters caliber, or 12 inches, 49 tons weight.

NEW KRUPP BREECH LOADING GUNS FOR SPANISH FORTIFICATIONS.

One of our engravings shows the great revolving crane by which the guns were lifted and placed on the truck for conveyance over a track to their intended position. This crane is worked by eight men, and readily lifts burdens of about 200,000 lb. The other engraving shows the jack frame and jacks employed to remove the gun from the temporary truck. At a range of 7,000 yards these guns are able to penetrate iron plates of two feet thickness.

By Mr. L. TETMAJER.

This memoir is the first of a series upon the unification of nomenclature and classification of building materials, undertaken by the author at the request of the Swiss Engineers' and Architects' Union. For its preparation numerous mechanical tests have been made upon steel rails, both good and bad, taken from the Swiss railways, while the corresponding chemical analyses have been made by Dr. Treadwell in the Polytechnic Laboratory, at Zurich. The results are given for twenty-two examples, about one-half of which have stood well, while the remainder have either broken, split, or suffered considerable abrasion in wear; but in many instances the mechanical test of tensile strength, elongation, and contraction, and the figures of quality (Wohler's sum and Tetmajer's coefficient) deduced from these have varied very considerably for the results obtained in practice.

The best wearing rails, which often give contradictory results with the tensile test, were comparatively pure manganese steels, low in silicon, only exceptionally up to 0.2 per cent., but generally below 0.1 per cent., and with less than 0.1 per cent. of phosphorus and sulphur. On the other hand, rails with a tendency to break or split are low in carbon, with variable proportions of manganese, but contain much silicon, 0.3 to 0.9 per cent., and often above 0.1 per cent. of phosphorus. Another series of experiments upon rails for the Finland lines made by the author in 1879-80 shows the high quality of manganese steel. These are essentially highly carburized (0.3-0.4 per cent. carbon) with 0.7 to 1.4 per cent. manganese, and have stood three and a half years' wear without a single one being broken; while those of silicon steel with 0.106-0.144 per cent. carbon, 0.592-0.828 manganese, and 0.423-0.435 silicon have failed in many cases, showing a great tendency to split. In both of the latter instances, however, the figures deduced from tensile tests of both good and bad specimens were substantially the same....