234 REPORT — 1871. 



On the Corliss Engine. By E. Dottglas. 



On tlie Gauge of Railways, By R. F. Faiblie, C.E. 

 Last year, at the Liverpool Jleeting of the Association, the author read a paper 

 " On the Gauge for Railways of the Future," in which he pointed out the capacities 

 of narrow-gauge lines, and showed how unfavourably the railway-system, as at 

 present worked, contrasted with such lines when properly handled. He said that 

 experience had confirmed the views he had then put forth ; and he showed, by 

 giving the dimensions of his carnages, both for passengers and for goods, that upon 

 a 3-f£ gauge he is enabled to place stock of ample size and of less weight than can 

 be done on the 3-ft. 6-inch lines. Whate^Tr saving may be efl'ected in first cost 

 may be lost sight of, the great advantage Ij'ing in the saving etiected in working 

 expenses. Every ton of dead weight saved goes towards securing tlie prosperity of 

 the line ; and if we can obtain the ample platform which the 3-ft. gauge gives, 

 combined with so much saving in weight, there is nothing left to be desired. In 

 concluding, the author referred to one or two prevailing errors which he said 

 existed vdih reference to the narrow gauge. 



The EJiysimeter, an Instrument for Measuriny tlie Speed of Flowing Water 

 or of Ships. By A. E. Fietchee, F.C.S. 



The principle involved in the construction of this instrument is the same as that 

 of the anemometer described by the author in 1869 (Brit. Assoc. Eeport, Trans, of 

 Sect. p. 48). 



A straight tube is placed in the cm-rent whose velocity is to be measured, and 

 held in a plane perpendicular to the direction of motion, so that the water Hows 

 across the open end of the pipe. This induces a tendency in the water of the pipe 

 to flow out, and so causes a partial vacuum in it. 



At the same time another tube, whose end has been bent round through an 

 angle of 90°, is held parallel to the straight tube in such a position that the bent 

 end faces the current. In this the lateral induction is nevitralized by the pressm-e 

 of the cun-ent. The difference between the pressures exerted in the two tubes by 

 the action of the flowing liquid is made a measure of its velocity. 



In order to accomplish this the tubes which dip into the stream are continued 

 upwards till their ends are on a level with the eye of the observer. These ends 

 are of glass ; they are united at the top so as to form in fact one tube, bent in the 

 shape of an inverted U- At the top of the bend, that is, in the centre of tliis 

 bridge-piece, is a small exhausting syringe or pump. By means of tliis a partial 

 vacuum can be formed in both of the long tubes whose ends dip into the running 

 water, and the water be made to rise through them into the glass tubes at the top, 

 which form the indicator of the instrument. The water is made to rise so far as 

 to fill but partially the parallel glass tubes of the indicator, in order that a com- 

 parison may be made of the heights of the columns. If the terminal tubes below 

 dip into still water, the heights of the columns will be equal, as they are held up 

 by the same pressure ; nor will it signif}^ if one of them is further immereed in the 

 water, for their upper ends are connected with the bridge-piece already mentioned. 

 But if there is motion in the liquid into which the terminal tubes dip, a difference 

 of height will be observed ; the amount of this diflperence can be measm-ed by a 

 conveniently divided scale, and from it the speed of the current known. 



It is interesting now to obsei-ve that the mathematical formulne which were 

 educed to show the relation between the speed of the current of air, and the dif- 

 ference between the heights of the columns of ether in the indicator of tlie ane- 

 mometer, apply correctly also to show the relation there is between the speed of the 

 cm-rent of water, and the difference of the heights of the columns of water in the 

 indicator of the rhysimeter. 



In the formula v- 



