ABSTRACTS OF SCIENTIFIC PAPERS 365 



XXIX. Sur V Application de la Methode Graphique a la Determina- 

 tion de Veffet utile des Machines. ' Association Fran^aise pour 

 1'avancement des Sciences, Congres de Rheims,' August 1880. 



[An abstract of the preceding paper.] 



XXX. On a Constant Flow Valve for Water and Gas. ' Transactions 

 of the Royal Scottish Society of Arts,' March 1876. 



The paper describes a regulator, invented and patented by Pro- 

 fessor Jenkin, by which the flow of fluid past an orifice is maintained 

 constant notwithstanding great variations of pressure on either side 

 of the orifice. An inlet pipe discharges into a chamber through an 

 equilibrium throttle valve. Above this is a partition which divides 

 the chamber into two parts. Part of the partition is constituted by 

 a piston, which is free to rise and fall, and is connected to the equi- 

 librium throttle valve below. The fluid passes into the upper part 

 of the chamber through an adjustable hole in the partition, and thence 

 to the delivery pipe. When the pressure of supply is excessive 

 the piston rises and throttles the entering fluid ; when the pressure 

 of supply is reduced the piston rises and opens the throttle valve. 

 The effect is to maintain a constant difference of pressure on the two 

 sides of the piston, and so to maintain a constant flow through the hole 

 in the partition, notwithstanding variations in the pressure against 

 which the fluid is delivered or in that under which it is supplied. 

 Several forms of the regulator are figured in the paper for the supply 

 of gas and water. The drawing of a large form, for use on water 

 mains, is reproduced by Professor Unwin in the article Hydro- 

 mechanics in the ' Encyclopaedia Britannica.' 



XXXI. On Friction between Surfaces moving at Low Speeds. By 

 Fleeming Jenkin and J. A. Ewing. ' Philosophical Trans- 

 actions of the Royal Society,' 1877, vol. 167, Part II., p. 509. 

 bstract, 'Pro c. P . S.,' No. 179, 1877.) 



This paper describes an experimental investigation of the influence 

 of velocity on friction at very low speeds, undertaken with the view 

 of seeing whether there is continuity between the friction of rest 

 and the friction of motion, when solid bodies rub against one another. 

 Under certain conditions the coefficient of friction between surfaces 

 at rest exceeds the coefficient between the same surfaces in relative 

 motion, and the authors looked for evidence of a possible continuity 

 between the two values in a rise of friction when the speed became 

 reduced. The friction of a steel axle in bearings of steel, brass, 



