PROTO-BATHYSPHERES 59 



applicable to various Uses; such as Fishing for Pearl, Div- 

 ing for Coral, Spunges and the like." 



Halley later devised a diving cap to which was attached 

 a long, flexible leathern hose (Fig. 13) , permitting a diver 

 to climb down and out from the air-filled bell, and to 

 walk about and work within the radius of his air-filled 

 tether. 



Later in the same century forcing-pumps were used for 

 the first time in connection with diving bells. 



Aroused to righteous wrath when someone claimed his 

 invention, one John Lethbridge of Newton Abbot, 

 Devon, contributed a detailed account of his experiments 

 to the September, 1749, number of Gentleman's Magazine, 

 Passing over the restrained controversy, we come to some 

 very interesting experiments: 



"Necessity is the parent of invention, and being, in the 

 year 171 5, quite reduc'd, and having a large family, my 

 thoughts turned upon some extraordinary method, to re- 

 trieve my misfortunes; and was prepossessed that it might 

 be practicable to contrive a machine to recover wrecks 

 lost in the sea; and the first step, I took towards it, was 

 going into a hogshead, on land, bung'd up tight, where I 

 stayed half an hour without communication of air; then 

 I made a trench, near a well, at the bottom of my orchard, 

 in this place, in order to convey a sufficient quantity of 

 water to cover the hogshead; and then tried how long I 

 could live under water, without air-pipes or communi- 

 cation of air; and found I could stay longer under water 



