In the annual report of the Hon. Van R. Richmond, State Engineer and Surveyor, noticed in our last, we find the following on the use of steam on our canals : ” Attempts have hitherto been made to substitute steam for horse power upon the canal. These have all thus far failed, probably from the fact, that the mach'nery used was not properly proportioned to the work which it was designed to perform, and that too high a rate of speed was sought to bo obtained. The law connecting the resistances offered to bodies moving in water with the power required to overcome such resistances, may be stated as follows : ” The resistance varies as the sgaare of the speed find the power exerted varies as the cube of the speed ; hence, if two horses were sufficient to tow a boat at a speed of two miles an hour, the number required to tow the same at a speed offour miles per hour would be (3—16 horses. It appears, therefore, in order to double the speed, the propelling power must be increased eight times. The obvious effect of the double speed would be to reduce the time of transit one half ; this, however, would be secured only at an expenditure for propulsion eight times as great as that due to a speed of two miles per hour. ” The foregoing determinations and comparisons are based npon the assumption that two horses will tow a loaded boat at a speed of two miles per hour upon the canal ; as shown by M. D'Anbuisson's formula, 44 per cent more power is re- Mcicwtific J^nmam. [October 23, 1869 times a large tub is filled at one dredging with all sorts of living specimens-shells, corals, shrimps, barnacles, sea- urchins, star-fishes, sponges, polyps, and sea-weeds, ,vith alt their natural brilliancy of tints." A water glass is also used which “ is nothing more than a square wooden tube, with a glass plate in the lower end. Sinking this under the water and looking through it, all the undulations of tho surface, which distort objects below, are lost, and nothing obstructs the vision. "Seen through this simple apparatus, the sea-bottom, or rather tho summit of the reef above which we were floating, was like the most exquisite aquarium, the contents of “which were ever shifting." London Bridge having become too narrow to accommodate the traffic over it, it is now proposed to widen it by throwing the foot-walks into the carriage-road, forming new footways up on cantilevers and brackets on either side of the road. This wi ll i ncrease the width of the carriage-way from thirty-five tofeet. Inventions Patented in England. By Americans. [Compiled from the “ Journal of the Commissioners 0f Patents,"] PROVISIONAL PROTECTION FOR SIX MONTHS. 2,405.—Manufacture of Boots and Shoes, and in Machinery or Apparatus Employed Therein.& mdash;N. A. Baldwin, Milford, Conn. August 29, 1869.' 2,640.-Spinnin g Mules.-Samuel Oddly, Manchester, England, Robert Nut tall, Bury, England, and John B. Smith, Wrapping Falls, N. Y. Sept. 8, 186!1. 2.664.—Fire Extinguisher.-G. F. Pinkham, Cambridge, Mass. Sept 11, 1869. 2,'745.—Spindles and Flyers of Spinning Frames.—J. Goulding, Worcester, Mass. September 21, 1869.
This article was originally published with the title "Steam Power on Canals" in Scientific American 21, 17, 267-268 (October 1869)