f *46 ] 
and fo occafion remarkable Differences of the Lengths 
of Day and Night, in the fame Revolutions, to 
Places under the fame Parallels of Latitude ; a whole 
Volume might be wrote in the Defcription, if the 
Author would defcend to Particulars. 
VII. A Machine for founding the Sea at any 
Depth , or in any Part , invented by Major 
Wm. Cock in the Tear 1738. in a Voyage 
to Georgia. 
Prefented April 10.’ g "tHE Draught of this Machine is 
I74 ° JL exhibited in Tab. II. Fig. i. 
wherein 
AAAA reprefent a Trunk of Timber, with afquare 
Hollow, thro’ the Centre of which paffes the fquare 
Piece of Timber BB. 
A Groove on each Side, in which are placed the two 
Pieces of Iron CC } the Foot of each refting on the 
Pins c D i D, that pafs thro’ the Trunk j the upper 
Part of the Irons are hooked to an iron Pin at E , 
which paffes thro’ the fquare Piece BB which 
Piece is hollowed between i/and H,(ot the Hooks 
of the Irons CC to pafs up and down. 
When the Weight F touches the Ground, the two 
Irons CC link the Trunk to G, which unhooks them 
at £5 whereupon they fall off, and leave the Trunk 
at Liberty to float or rife up again to the Surface. 
A Machine of thefe Dimenfions, loaded with an 
iron 'Ball, F, of 12 Pounds Weight, being let down 
in 
