222 APPLIED SCIENCE 



than would be supposed. With the ' Great Eastern ' as a point 

 i'appui the variation was hardly sensible. Another array of 

 patents defends the privilege of laying a cable through a long 

 auxiliary tube ; four patents for this contrivance were taken out 

 in 1857. Other gentlemen wish to tack floats on to the cable ; 

 others, parachutes ; others, gum and cotton, so as to buoy the 

 cable up for some time ; then the gum or glue dissolves and lets 

 the cable down quietly. It is both amusing and sad to read 

 these and many other contrivances. Surely the man who makes 

 a bad invention, and, believing it to be good, spends his life and 

 his fortune in the vain attempt to achieve an impossible success, 

 is almost as fit a subject for commiseration as the real inventor 

 who fails to reap his just reward ; and then the former class are 

 much more numerous than the latter. 



The machinery now in use for laying cables acts extremely 

 well ; if the cone and rings were in general use, no further im- 

 provement would be required. An experiment by Messrs. 

 Siemens Brothers to use a reel mounted on a turn-table in the 

 ship's hold and driven by a steam-engine, deserves notice, and 

 to some extent praise, as, at any rate, an experiment out of the 

 beaten track ; but the experiment was not successful. Captain 

 Selwyn has proposed a floating reel, the speed of which would 

 be regulated by the floats of paddle-wheels ; but contractors who 

 have achieved success by the old plans will be slow to tempt 

 fortune by trying these novel contrivances. It will be seen that 

 very little improvement has been made in the paying-out 

 machinery of late years, simply because it was not wanted. 

 The cone and rings date from 1855 ; the Appold's brake from 

 1858 ; water-tight tanks were first made in 1858 for the Red 

 Sea Cable, but first used by Messrs. Gisborne and Forde for the 

 Malta-Alexandria Cable in 1.861. Since then no material 

 change has been made in the arrangements. 



It is far otherwise with the electrical tests during sub- 

 mersion. 



The object of tests during submersion is twofold : first, to 

 detect instantly any injury which may occur ; and, secondly, to 

 ascertain the position and nature of the injury. Time is of 

 extreme importance in these tests. Faults on board almost 

 always are caused at or near that part of the cable which is in 



