Author: Franklin Institute

Publisher:

Published: 2015-07-20

Total Pages: 452

ISBN-13: 9781331880981

Excerpt from Journal, Vol. 19: Of the Franklin Institute, of the State of Pennsylvania, for the Promotion of the Mechanic Arts Fifth Trial, June 9, 1841.Immersed Float Surface reduced to 22 sq. ft. area, and reefed-up 11 inches; or reducing the diameter of the wheel 22 inches. Number of revolutions made by engines per minute, 27 1/4. Speed of vessel in statute miles per hour, 9.124. The barometer stood at from 25 to 26 inches. Which result was nearly equal to her former speed (viz. 9.174) in 1837, with rectangular floats of more than double the immersed area of the trapezium floats. Experiments with Towing as per accompanying Table. In June, 1841, the "African" towed the "Numa" transport of 323 tons, at the rate of 5 1/2 statute miles per hour. In July following, she towed H. M. steam frigate "Dee," of 704 tons, and 200-horse power, 5 statute miles per hour, - which was only 16 miles per hour less than her greatest speed when propelled by her own engines, or 6.6 miles per hour. The official report, on the following page, only differs by half a mile between the towing powers of the "African," with her rectangular floats, in 1837, and the trapezium floats, in 1841; so that, considering that the area of the trapezium floats was merely adapted to propelling the "African" simply as regarded speed, these trials could hardly be taken as the criterion of their powers as applied to towing, when the areas should have been increased expressly for that purpose. But, comparing the whole of the experiments, hen tried in still water under the most favorable circumstances, and when tried in the "African," under the unfavorable circumstances of foul bottom and difference of the powers of the engines, the conclusion is in favor of the trapezium floats. The truth of the principle is confirmed by Mr. Ewbank, and by the laws which govern the forms of the tails of fishes, the feet of aquatic birds, and the wings of birds and insects, whereby the means are so admirably suited to the ends; and the triangular form proposed by Mr. Ewbank for paddle floats entirely confirms the view I took of the subject in the years 1839 and 1840. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.