360 On propelling Vessels by Means of Windmill Sails. (Nov. 



around the same shaft.* Query. Might not those sails, or eYen, 

 those of the Portuguese windmill, be advantageously employed 

 as auxiliary means (should such be found requisite to propel 

 ships of the greatest dimensions) as the stud or stay-sails, Sec. of 

 ships are in light breezes 1 and instead of being confined to three 

 rectangular, or elliptical sails, might not the number be increased 

 to embrace a surface nearly equal to the present sails of a ship 

 ■when set? Independently of those means, or the improvement 

 of the common rectangular sail, a considerable accession of 

 force, I am convinced, might be obtained by an attention to the 

 construction and more scientific application of the paddles 

 themselves. The present form was adopted in the infancy of the 

 invention of steam-boats ; and, although numerous experiments 

 have been tried without, unfortunately, any practical good having 

 resulted from them; it is yet evident that much remains to be 

 done. From the circumstance of half the wheel only being sub- 

 merged at any one time during its action, it follows that the 

 wind must oppose a very considerable resistance to its rotatory 

 motion ; the effect of which may be more easily conceived when 

 it is known that it performs upon an average 40 revolutions per 

 minute. Hence an incalculable advantage would be obtained 

 could the paddles be brought to present a smaller surface to the 

 retarding force of the air, similar to the oars of a boat, which are 

 said to be feathered when their edges alone are opposed to the 

 wind during the interval of the strokes. As my present propo- 

 sition is to apply another power to the machinery in use, I will 

 trust to experience more matured to suggest a remedy for this 

 defect in the mechanical propulsion of vessels by steam or other- 

 wise. A few of the advantages which this plan, if adopted, 

 would possess over steam, have been already detailed ; that it 

 would possess as great a superiority over the present mode of 

 navigation must be equally evident ; for, whilst it would share 

 with steam the singular advantage of sailing against winds or 

 tide, whereby navigation may be rendered comparatively safe, 

 the simplicity of the method proposed would render it infinitely 

 preferable to both. Masts, sails, ropes, spars, &c. form no 

 inconsiderable share of the sum total of a vessel's cost; and to 

 a maritime nation, they become of national importance, when, 

 derived from foreign sources. 



What the author now submits to the public is at best but a 

 hasty sketch. He has merely embodied those ideas which 



its circumference); therefore alliming ' the circumference of the axis tobe^Qfthe 



Tuofoq 



circumference of the circle described bv the revolution nf a sail, in that cnw> each 

 sail will have the power of f>70,«208 x 82 = 2L4lo,B56 lb«. and the who!* ellipsis 

 six tin.es that ; viz. 188,07&,«J3o lbs. or capable titiCh oving 574J torn. *x<ft&l'£fc 

 of friction." 



« See Dr. Gregory's Dictionary, of Arts and Sciences .:, Art. Windmill. . 



i. r-.iTi U'i 



