The engraving shows a new form of brake shoe designed particularly for street cars. The rubber or friction block has the usual concave rubbing surface, and is made of wood sawed out across the grain. This presents a better grip or hol d on the wheel t han a meta l shoe, does not wear out the wheel so rapidly, and is cheap and durable. The metal backing, Fig. 2, is of arched form, and is provided with a single side flange and opposite hook shaped ends that enter similarly shaped recesses made in the ends of the block, which is thus held securely from splitting, and, only being bound on one of its sides by the metal head, may be easily removed on aking out a holding screw, Fig. 3, and be replaced byanother without removing the whole shoe from the brake bar. The entire shoe may be carried in the usual manner. This invention has been patented by Mr. J. H. Pitard; information can be obtained from Messrs. Goldsmith & Pitard, P. O. box 334, Mobile, Alabama. Battery with Two Liquids. The author succeeds in suppressing the nitrous vapors of the Bunsen battery by using a depolarizing liquid, consisting of nitric acid in which 75 grs. potassium dichromate have been dissolved per liter. In contact with the zinc he employs either acidulated water or potassium disulphate—A. Dupre.
This article was originally published with the title "Improved Brake Shoe" in Scientific American 52, 25, 386 (June 1885)