APPENDIX. 355 
^74. i expreffes the Number of Stroaks with 
which all fides of the Bomb are (truck, at 
the fame Inftanc and with the fame Force that 
the Hammer ftrikes the aflien Pin, for com- 
prefled Fluids pre(s equally on all Tides : And 
as chefe Stroaks of the Hammer would Toon 
have diftended and burft a Sphere of dudile 
Silver, fo the Water was by this means much 
more forcibly compre(Ted in this Bomb than 
in the Silver Sphere of the Academy of Cimento. 
Observation XIL 
Plot in his Hiftory of 0 xfordjh ire ob- 
JL>/ ferves, that Rivers are found conftantly 
to freeze fir ft at their Bottoms: And the fame 
is al(b obferved by Watermen and Fifliermen, 
in the Thames both within the reach of the 
Tide and alfo above the Tide ; who not only 
feel it at the Bottom with their Poles, a con- 
fiderable time, viz» feme Days before the 
Surface of the Thames is frozen over, but 
fee it alfo rife up from the Bottom with fuch 
Force, as to dart up in pieces 'edgeways half 
a Foot, and fometimes a Foot above the Sur- 
face of the Water, in which Pofture it con- 
tinues a little time, and then turning fiat on 
the Surface of the Water, it is carried in 
A a 2, great 
