180 Proceedings of Royal Society of Edinburgh. [sess. 
may therefore safely conclude that the warming of the water 
between midnight and early morning was not due to atmospheric 
influence. The simple reason is, in fact, not far to seek. By 
whatever processes the daily heating of the waters is produced, it 
Table D. — Table Shotving Convection During Cooling. 
Station. 
Hour. 
Surface 
Temp. 
Aii- 
Temp. 
Station. 
Hour. 
Surface 
Temp. 
Air 
Temp. 
193 
7.40p. 
26-9 
27 '6 
233 
12.30p. 
26-9 
30'2 
194 
11.45p. 
26-5 
234 
la. 
26*6 
195 
6a. 
27-1 
26-0 
235 
5.55a. 
27-0 
26-5 
210 
5.30p. 
26*6 
28-0 
238 
6.5p. 
27’4 
28-1 
211 
12.20a. 
26-9 
239 
12.1a. 
27*2 
212 
6.10a. 
27-8 
25 ’6 
240 
6.45a. 
27-6 
26'6 
213 
5.35p. 
28*3 
26-9 
243 
12-lp. 
27-8 
27-6 
214 
12.30a. 
27-5 
244 
la. 
27*2 
215 
6.8a. 
28-1 
26*7 
245 
6.14a. 
27-2 
26 *5 
217 
2. lOp. 
28*3 
28*5 
253 
4.2p. 
27*1 
27*8 
218 
12.15a. 
27-6 
254 
12.20a, 
25-9 
219 
6.30a. 
277 
26 -0 
255 
6.10a. 
25-9 
2*4*6 
220 
3.10p. 
28 T 
27-5 
257 
2T0p. 
26-3 
26-5 
221 
12.30a. 
27*2 
258 
12.30a. 
25*8 
222 
6.10a. 
27-4 
27 '3 
259 
6.10a. 
26-1 
2*4-2 
223 
6 P . 
28*3 
27-9 
260 
2. lOp. 
27*0 
27-6 
224 
12.30a. 
26-9 
261 
12.30a. 
26-5 
225 
6.15a. 
27*8 
27 T 
262 
6. 30a. 
27-0 
27-3 
226 
6p. 
28-1 
28-3 
268 
1.45p. 
24-1 
24’5 
227 
12.30a. 
27*3 
269 
12.10a. 
23*4 
223 
6.10a. 
277 
28*5 
270 
6.10a. 
237 
23 -2 
229 
3.15p. 
27 ’9 
30-0 
272 
2.45p. 
26*3 
27-6 
230 
12.20a. 
26-8 
273 
12.10a. 
25-6 
231 
6.5a. 
267 
27'5 
274 
6.20a. 
24-6 
23-9 
is evident that as the sun sinks the surface layer of the water will 
begin to cool by radiation. Suppose it to cool by half a degree 
centigrade : it will then become denser than the slightly warmer 
