546 PHILOSOPHICAL TRANSACTIONS. [aNNO J 721. 



because they would be supported at every vibration, which is only of three 

 feet. Besides, in the use of inclined oars, more than half the time is lost in 

 raising and recovering the oar, before they give the stroke; which makes the 

 vessel move by fits and jerks, so that the people aboard feel every stroke of 

 the oars when they play; whereas the revolving oars always move equally, and 

 succeed each other without loss of time ; which makes the vessel move uni- 

 formly, without affecting those who are aboard. 



It is to be observed too, that a galley built on purpose for the use of inclined 

 oars, would not be so proper as another vessel for perpendicular oars ; because 

 the galley has a considerable length, and but little height above the water. 



The author then states a comparative experiment between his galley with the 

 machine oars, and a common galley, in which their appears to be very little 

 difference between them, either way. 



On another experiment, performed by M. Chazelles, a member of the Aca- 

 demy of Sciences, it is stated that the experiment made of the new machine, 

 though defective by reason of the difference with respect both to the crew and 

 the vessels, yet it leaves room to expect a considerable advantage from this in- 

 vention, in giving the ship way ; for though the common galley should keep 

 up with the machine galley at their first setting out, with an equal number of 

 hands; the machine galley will get the better at long run, when the other crews 

 are so fatigued, as to be obliged to row by turns. For here the men will hold 

 out a longer time, their action not being so great, nor so violent. Besides, 

 having only 200 men employed, and being equally manned with the other 

 galley, fresh hands may be supplied, and so they will continue to go at the 

 same rate: for in case of need, the marines may be employed in this service; 

 which they will perform with as little reluctance, or trouble, as they work at 

 the capstan. 



The reason of this increase of velocity appears plain, if we consider the dif- 

 ference between the common way of rowing, and that by perpendicular oars : 

 the last is done by an uninterrupted application of force, in the same direction ; 

 the other acts by jerks. And, of the three parts of action that are employed, 

 in order to give the strokes; one in raising the oar out of the water, the second 

 in advancing the hands forwards, and the third in pressing against the water; 

 only the last turns to account : and that still loses something of its efficacy ; 

 for the crew, by their falling back all together, make ihe vessel plunge, and 

 render its motion oblique, which contributes very much to its decay. 



These are not the only defects of the common oars; for, in order to aug- 

 ment their force, the number is to be increased, and consequently the vessel 

 must have a greater length ; by which means it is rendered weaker, and less 



