204 Proceedings of the Royal Physical Society. 
Variability of 
Earth Thermometers. Temperature, 
Earth Thermometers. 
3 ae rt 3 12 = 
ins. |12ins. 22ins.|Temp.| 3ins. | 12ins. | 22 ins. 
atda.M Temp. 
| | 
January, 5 : ; oe ites, ae | ee 
February, Sis As Sogo | mob: oat Gwe = 
Marchs #.9s3 0s 4 eA See wee | wee ee | 
OAS 010) Peer peer i eee? aeons ea fe roc | ce | eel es =A 
May, . = fe | 6058 125020) |} 53°34) 5 759 270) OS Oe aaa 
June, 58:7 | 56:8 | 54°99 | 58°99 | 22 | 06 | 06 | 37 
BLY eee ey | OT) OL 7, | 066 | O84) 1k OTe ee ees 
August,. or | 58:5: | 08:3 41 571) 58:9 | 1-9s 0:50 TO a 
September, . | 55°8 | 56°8 | 56-0 | 58°7 | 2:7 | OS | O4 | 493 
October, . Se ASFA 482901 49-3 944-0) a0 0:8 0°5 2°9 
November,. . . . | 40°9 | 42°77 | 48°3 | 42° | 1°38 | 06 | 0-4 | 3:1 
December, . . . . | 35°38 | 38°5 | 39-7] 38°0 | 1-7 | 06 | 03 32 
Year, | 
XV. River Temperature. Part III. Comparison of the 
Thermal Conditions of Rivers and Ponds in the South 
of England. By H. B. Guppy, M.B., F.RS.E. 
(Read 18th March 1896.) 
In their thermal behaviour rivers and ponds present some 
points of striking contrast, and these differences no doubt 
find some expression in the composition of their respective 
floras and faunas, as well as in the habits and life-history 
of the plants and animals concerned. Whilst not broaching 
upon a very novel subject, the writer here endeavours to 
give scientific precision to differences in the temperature of 
ponds and rivers, such as must have often come under the 
notice of the experienced angler and the field naturalist. The 
observations covered about two years, and were made on the 
Thames at Kingston, and on the numerous ponds in that 
neighbourhood. In the first part of this paper some of the 
principal features of the thermal regime of the Thames were 
discussed, and the surface-temperatures of rivers and ponds 
were there contrasted. In alluding again to some of the 
