182 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
over 120 hydrographic soundings, make the conclusion 
inevitable that the Irish Sea is a practically homo- 
thermic water mass, and that the small differences indi- 
cated by the soundings are purely “ accidental,’ in the 
sense that they have nothing whatever to do with a real 
temperature stratification, nor are they indicative of the 
existence of deep water currents. The results of the 
observations of 1907-8 are tabulated as follows :— 
Mean Difference | | 
| | 
| Mean Surface and Maximum Minimum 
Station. | Depth. Bottom | Difference. | Difference. 
_ Metres. Temperatures. 
sb C aC: 
| | 
i Se eee ee 
| I 27:5 2-45 | 3-8 0-1 
hy poses Ieee 0-70 Pape: 0-1. 
Piel to Calf ~ 
of Man | III | . 36-5 0-32 0-6 0-15 
IV | 405 | 0-17 ti! same 0-05 
V 72:5 1-14 2-23 0:05 
Calf of 
Man to 4 VI 57°5 0:4. 0:7 0-1 
Holyhead | 
VEE 57:5 0:22 0:35 0-1 
a 65 0-42 0-75 O-1 
Welsh Bays + IX 39-5 0-6 1:2 0-1 
| xX 38:5 0:62 1:2 0-05 
Now, considering these figures, we see that the 
greatest difference in temperature between superficial and 
deep layers’is to be found, not in the deep water, but in 
the shallow water near the land. Thus the mean 
difference is greatest—2°45° (.—-at Station I, which is 
about ten miles from the coast, and is the shallowest of 
