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XVI. An Investigation of the Laws which govern the Motion of Steam Vessels, deduced 

 from Experiments. By Peter W. Barlow, Esq., Civil Engineer. Communicated 

 hy Peter Barlow, Esq, F.R.S. 



Received May 8, — Read May 29, 1834. 



J- HE increasing extent of steam navigation, and its importance to the welfare of 

 this country, demand a strict attention, not only to the construction of the vessels, 

 but to the application of the power of steam, in order that the greatest possible use- 

 ful effect may be produced with a given quantity of coals. The action of paddle- 

 wheels, although a subject strictly mathematical, has hitherto but little engaged the 

 attention of scientific men ; in fact, the motion of the vessel being horizontal, while 

 that of the wheel is rotary, there result a certain peculiarity and complication of 

 action which almost defy the theorist to unravel without the aid of a complete set of 

 experiments ; for the great commotion of the water in the neighbourhood of a steam- 

 vessel is such, that the results calculated from the usual laws of the resistance of 

 fluids would scarcely be considered satisfactory without having the means of com- 

 paring them with practical results. In this respect I have been very fortunately cir- 

 cumstanced ; all, or nearly all. His Majesty's vessels are fitted out at Woolwich, and 

 each vessel is submitted t<^an accurate experiment, to ascertain its speed before it 

 leaves the river, sometimes light and sometimes laden. The exact amount of their 

 cargoes is known, their registered and actual tonnage, area of paddle, and every 

 other particular which can serve as a guide to such inquiry ; and I have availed 

 myself of these circumstances, and of my personal acquaintance with many of their 

 officers, and the officers of the yard, to attend several of the experiments myself, and 

 in other cases to obtain an exact record of them. I am in hopes, therefore, that 

 some of the remarks in the following pages may not be without utility as a future 

 guidance in the practice of steam navigation. 



Within a few years, several of His Majesty's vessels have been fitted out with 

 wheels of a new construction, in which the floats are so contrived as, by the aid of 

 machinery, to enter and leave the water nearly in a vertical position. This is found 

 to reduce the shock on the engine produced in common wheels by the floats enter- 

 ing the water, and, in cases of deep immersion, to give an increased speed to the 

 vessel. 



A wheel in which the paddle should enter the water in a vertical position has long 

 been considered a desideratum to remedy the supposed loss of power from the oblique 

 action of the common wheel ; and various methods of effecting this object have been 



MDCCCXXXIV. 2 s 



