Of FREEZ ING WATER. 25 



but could not find it, as there was about 3^ feet of fnow on the 

 ground. 



22. — I WATCHED this fhell about an hour, when, being 

 called out on bufinefs, I found, on my return, three hours af- 

 ter, the plug gone, and the icy cylinder 2^ inches high. Plug 

 loft. 



23. — I HAD a plug made, and jagged or notched along the 

 fides, to prevent its being forced out fo eafily ; and watched 

 this (hell for upwards of three hours, going into the houfe at 

 intervals to warm myfelf. The laft time I went in was about 

 half an hour after twelve, when, after a few minutes, I heard 

 a fort of hiffing found, upon which running out, the plug was 

 gone, and a cylinder of ice fhot up, exceeding any of the for- 

 mer, being 6~ inches high. Plug loft. 



24. — A SIMILAR plug to the laft. I watched this with more 

 fuccefs ; for although abfent at intervals > yet at half paft four 

 in the afternoon, (therm, at 6°) I faw the plug fiiddenly forced 

 out by the column of ice, accompanied by the hifling noife j 

 and, obferving its fall, I found it at 62 feet from the fhell. 

 The icy cylinder was 4 inches high, and the fuze-axis of the 

 fhell I found lay nearly at an angle of 80° with the horizon. 



31. — Concluding from the foregoing experiments, that no 

 plug could be fo fixed, as to render the refiftance at the fuze- 

 hole greater than at the weakeft part of the fhell, in which cafe 

 I fuppofed it would burft, (which was the primary objedt in 

 thefe experiments) I thought it might be worth while to obferve 

 how far the force of congelation would projedl a plug of a given 

 weight and figure, and forced in with the fame number of 

 ftrokes of the fledge hammer. For this purpofe, I placed the 

 fuze-axis of the fhell at an angle of 45 ° with the horizon, and 

 on the 31ft of December 1784, being the coldeft day of this 

 year, the plug was projedled whilft I was abfent, a cylinder was 

 Ihot out, in the diredion of the axis, of 7?^ inches, and not in- 



VoL. II. d cUning 



