3o6 Literary and Philosophical Society. 



this mode of pressing water against water (though simple 

 and plausible at first sight) is the most wasteful expen- 

 diture of propelling force of any that has been proposed. 



* It appears that " endless chain-floats " have been many 

 times proposed and patented ; but this plan, too, is de- 

 fective in principle, and has always failed in practice. 

 The chain-floats are driven horizontally, and successively 

 acting upon the same column of water, generate a current 

 in the direction of their motion, and much of their pro- 

 pelling power is lost by moving and agitating the water. 

 In an experiment I witnessed in 1813 (in a boat on the 

 Bridgewater Canal), the floats were placed about four feet 

 apart, and when first started, the boat moved with con- 

 siderable speed ; but as the speed of the floats increased, 

 that of the boat decreased. Then every other float was 

 removed, and at a new start better speed was obtained, 

 but could not be kept above three miles the hour. Then 

 all the floats were removed, and the chain only dragged 

 through the water ; this carried the boat a trifle faster than 

 the floats had done. 



'In 1795 Lord Stanhope made experiments with a 

 steamboat with the '' duck's-foot paddles," which did not 

 succeed. The defects of this form of propelling arise from 

 the loss of time in withdrawing the paddle between each pro- 

 pulsion, and in the waste of power in this retrograde motion. 



' In 1795, James Rumsay, of Virginia, constructed a 

 steamboat, which was tried on the Potomac in 1787, and 

 which sailed by means of steam four miles an hour, as 

 stated in Dr. Rush's letter to Dr. Letsome ; but the boat 

 was not continued on the Potomac, and Rumsay after- 

 wards tried his plan in London without success. About 

 the same time, Mr. Fitch of Philadelphia made experi- 



