Produced by Juliet Sutherland, Lesley Halamek, and the Online Distributed Proofreading Team at http://www.pgdp.net [Illustration] SCIENTIFIC AMERICAN A WEEKLY JOURNAL OF PRACTICAL INFORMATION, ART, SCIENCE, MECHANICS, CHEMISTRY, AND MANUFACTURES. NEW YORK, DECEMBER 14, 1878. Vol. XXXIX.--No. 24. [NEW SERIES.] [$3.20 per Annum [POSTAGE PREPAID.]] * * * * * CONTENTS. (Illustrated articles are marked with an asterisk.) Alum in baking powders Alum in bread 376 Argonaut, or Paper Nautilus* 375 Astronomical notes 377 Babbitt metal, to make [5] 378 Belts, rubber, slipping [6] 378 Bench, saw, Casson's* 374 Boot polish liquid [8] 378 Butter, to color [16] 378 Canal, ship, Belgian* 367 Economy, machine shop 371 Eggs, preservation of 375 Electric light, Werdermann* 373 Engineers, warning to 367 Engine, steam, valve yoke [48] 379 Exterminator, roach [57] 379 Filter for rain water [19] 378 Foot power, new* 370 Glass, iridescent 368 Glass, to make a hole in 375 Hair, to prevent falling out [42]379 Inks, sympathetic 377 Invention, reward of 371 Inventions, new, 370 Inventions, new agricultural 377 Inventions, new mechanical 374 Inventors, bait for 374 Iron and steel, preservation of 367 Iron, malleable, to make [43] 379 Leaves, culinary uses for 370 Line, straight, to draw* [36] 379 Mechanics, amateur* 371 Mexico, progress of science in 376 Microphone as a thief catcher 375 Naphtha and benzine 377 Nitrate of silver, reduction of 377 Notes and queries 378 Oil notes 372 Petroleum and gold 377 Petroleum, progress of 368 Poultices 374 Quinine, effects of on hearing 374 Railroad, first in U. S. [2] 378 Rails and railway accidents 368 Railway notes 373 Sanitary Science in the U. S. 369 Screw heads, blue color for [4] 378 Sheep husbandry, American 375 Shutter fastener, new* 370 Silver mill in the clouds 374 Spider, trap-door* 375 Sprinkler, garden, improved* 370 Telescope, sunshade for [3] 378 Tools, steel, to temper [55] 379 Tree, tallest in the world 375 Tree trunks elongation of 376 Trees, felling by electricity 370 Tubing, to satin finish [51] 379 Vise, an improved* 370 White lead, to test [14] 378 Wire clothing for cylinders* 377 Work, the limit of 368 * * * * * THE BELGIAN SHIP CANAL.