960 



6. " On the Temperature of Steam, and its corresponding Pres- 

 sure." By John Curr, Esq. Communicated by J. Scott Russell, 

 Esq., F.R.S. 



In this paper, which is a continuation of a former paper bearing 

 the same title, the author states that the law given in that paper, in 

 reference to steam when superincumbent on the water in the boiler, 

 may be rendered applicable to the determination of its pressure 

 when insulated therefrom, as in the case of the expansive engine, 

 of which the cylinder being in part filled with steam of the same 

 temperature as that in the boiler, the communication is suddenly 

 cut off, and the stroke is completed by the pressure on the piston 

 of the steam whilst expanding within the cylinder. He considers 

 that the power of expansive engines has been greatly overrated, in- 

 stancing those of the Great Britain, which were of the estimated 

 powTr of 1200 horses, but which he states he can prove did not 

 exceed in actual power that of 300 horses. This he attributes to 

 the inapplicability of Mariotte's law without a particular limitation. 

 Having premised that " it is assumed that, by nature's law in the 

 generation of steam, of the temperature 100° and of a pressure of 

 15 lbs. on a square inch, the density of the Matter of Heat, is to 

 that of atmospheric air of the same temperature and pressure ex- 

 actly as 1 to 2," he then gives general laws, by means of which, he 

 considers, the pressure of steam when cut off from its generating 

 source may be correctly estimated. 



" In conclusion," the author states, " it may be said that, this and 

 the former paper, both professing to give laws relative to the pres- 

 sure and temperature of steam, independently of experiment^ the 

 theories proposed must in general be accepted as absolute truths, in 

 case of being verified by experiment, or taken as vain attempts to 

 subvert laws already firmly or suflficiently established." 



7. " An Experimental Inquiry into the strength of Wrought Iron 

 Plates and riveted Joints as applied to Ship-building." By Wil- 

 liam Fairbairn, Esq., F.R.S. 



The object of the author was to determine by direct experiment 

 the strength and value of rolled iron plates and bars of different 

 forms in reference to their application to ship-building, and the con- 

 struction of other vessels exposed to severe strain. 



The experiments described in this paper were conducted with 

 great care, and the irons used were purposely selected from those 

 districts where the largest quantities were manufactured. The 

 relative strengths of each kind, as also the deductions, are given in 

 the order in which the experiments were made. 



The author found the tensile strength of plates, when torn asunder 

 in the direction of the fibre, and when torn asunder across the fibre, 

 as nearly as possible the same. This fact is derived from twenty 

 distinct experiments, and he attributes this equality to the improved 

 method of manufacture which of late years has been introduced. 

 This new system is described as rendering the plate more uniform 

 by crossing the layers in the process of ' piling,' thus forming an 

 alternate series of laminse, whose fibres cross each other in the body 

 of the plate. 



