240 REPORT— 1871. 



diminishing in beiglit as the level of the lake is lowered, till at last it is nothing, 

 when the level of the lake comes to the same as that of the highest pool. After 

 that, when the surface of the lake gets too low to give the statutory or requisite 

 supply of water over the uppermost stop, the uppermost sluice is shut, and the 

 one next in order of descent is opened, when the fish would have one leap fewer 

 than before, entering the lake bj^ leaping over the second sluice, and then in suc- 

 cession as the level of tlie lake falls over each of the other sluices, having a leap 

 less at eveiy change, till at last, when the lake comes to be lowered to nearly the 

 level of its lowest outlet, there would be only one leap to take. 



On a new System of Warming and Ventilation. By J. D. Moerison. 

 The author called attention to his paper which was read at the Exeter Meeting, 

 and stated that he introduced improvements which had been approved of bv the 

 Highland and Agricultural Society of Scotland. He liad also built an experi- 

 mental room, where his system of ventilation might be tested pi-actically. 



Chain-Cahle Testiny, and projyosed New Testiny-Linh. 

 By E. A. Peacock, C.E., F.G.S. 



It is proposed to provide " testing " -links for each new cable, one link to be con- 

 nected mth the cable at each of its ends, and another link to form part of the cable 

 at every 15 f;ithoms. Each new link will be a flat oval piece of wrought iron, 

 whose thickness will be equal to the diameter of the metal of each ordinary link. 

 The new links will be cut out of a plate of iron, by means of a steam-punch, and 

 will be left by it of the oval form and having three circular holes through, one in 

 the centre and another halfway to each end. The use of the centre hole, wliich 

 will be 1^-inch diameter for a l-inch cable, is this .-^a piece of cylindrical bar iron, 

 about G inches long and a shade less than li-inch diameter, is to be inserted into 

 this hole, and by means of this bar one of the 15-fathoni lengths can be connected 

 with a hydrostatic press, the other end of the " length " being fastened at the 

 opposite end of the platform by means of another 6-inch bar, and then the testing- 

 strain may be applied. The two other holes are to connect the testing links with 

 the adjoining parts of the cable. 



A cylindrical bar of South-Wales iron was tested by the late Mr. Telford, and 

 its increase of length was found to be 11-G8 per cent. After the test, and its di.a- 

 nieter was reduced from 1| inch to IJ, it was torn asunder by 43 tons 11 cwt. 

 Therefore if the "length " of 15 fathoms is increased by testing to an amount ex- 

 ceeding (say) 8 per cent, of its original length, its diameter, and consequently its 

 streuf/th, will have been too much reduced, and it ought to be condemned. When 

 the stretching is confined within- moderate limits so as to justify the tester in 

 stamping and passing it, the actual length may be stamped on the testijig-link ; and 

 then, when the cable has been exposed to severe strains on service, it may be laid 

 straight along the pier, and each length be remeasured to ascertain if the strain has 

 been too great, and if any part ought to be condemned. 



Links have been found to be cracked after having apparently withstood the test ; 

 therefore each length, after being tested (before being stamped), should be lifted 

 upon & well-lighted bench of the height of a table, and then every link should Ijo 

 exammed carefully all over with a magnifpng-glass. If any link is fouud to be 

 cracked, or otherwise defective, the "length " of coiu-se ought to be rejected. 



On the Carbon Closet System. By E. C. C. Stanford, F.C.S. 



On tlie Steam Blast. By C. Wiiliam Siemexs, F.R.S., D.C.L., M. Inst. C.E. 

 After describing what had previously been done by others, including the re- 

 searches of Professors Zeuner and Eankiue, the author explained an improved steam- 

 blast apparatus which he had invented. This apparatus consisted of tlirec principal 



