1833.] Means of making Ice by the Natives of Bengal. 87 
ice-fields, 48°. The very cold nights are from six to eight in one season, 
or in which the thermometer is below 48° at Bandel, or in the ice-fields, 
42°. The careful record of last season shews there were 27 nights on 
which ice was formed, of which only three nights were very favourable, 
seven favourable, and 17 less so. 
As the influence of straw in producing the necessary degree of cold 
must be considerable, the following experiments were tried. One of the 
common unglazed dishes was placed at the bottom of one of the ice-~ 
beds, with a very small quantity of straw between it and the earth, and 
another dish of the same kind was placed in the same way without any 
straw under it. Next morning I found ice had formed upon the water 
in the dish which was put upon the straw in the ordinary way, but 
there was none on the dish which had been placed without, nor on 
another at the bottom of the ice-beds ; the water in the dish upon the 
sprinkling of straw being at 50°, and the other upon the earth at 52°. 
Soon after sun-rise on the same morning, the water in an ice plate, 
put upon the walk between the ice beds, stood at 46°, and in the large 
water jar between the beds at 60.5°. 
As a further proof of the influence of straw in producing the degree 
of cold necessary for forming ice, a register thermometer was placed 
upon the straw with its bulb exposed to the sky near the side of one of 
the beds, after several of the plates had been removed, when it was 
found to indicate as follows :— 
2 |'Tempera-|Difference be- 
Time res CU es a : : FE ture of the|tween the air 
Beis # 1% lair 4 feetlat the surface 
Date. -——]-- oe | a 1 Ie g |above the |ofthe straw & 
= eb ue | tb 5 g paar 3 -§ | beds. 4 feet above it, 
‘sie FI se he aH [a] Ss le : ; 
5 2 Pi haem ea SS ee emt nS > 
= cs = |e aA lala] = cs) 
1832. 6 © é 0 6 oO | 6 ie) 6 oO $ 
Jan.20.|7 a.M.| -. |) 28: | .. |covered|26 47 | 65 | 21 oe 
22.17 a.M.| 5 P.M.| 47 | 70 . nit 121 42. 5 48 a Ne 60 
23.)7 a. M. Se 34 | .. |covered|/29.5] 114/34 | 47 |. 17.5 ee 
BE lh... |) Shri ...4 59 nor TIA), 3 sill ia si: 4 ae 
all Dias ats .. | .. ‘covered! 29 | 124 0 
This table presents a high maximum and very low minimum tempe- 
rature, which is to be explained by the non-conducting and powerful 
radiating property of the straw, &c. and, in the morning, in part to the 
production of hoar-frost. 
As the kind of dishes employed must have a considerable influence on 
the temperature of the water they contain, I employed the following 
means to detect the influence of the material of which the dishes were 
formed. A morning was selected when the wind had suddenly changed 
