22 



Fishery Board for /Scotland. 



In Fig. 5, we have a representation of the mean thermal " isanom- 

 alies " of our seas, as compared with the mean annual temperatures 

 along the meridian of 15° W. And here we encounter a certain in- 

 evitable difficulty, from the fact that neither this nor any other 

 meridian in the North Atlantic can serve us throughout as a true 

 standard of oceanic conditions, unaftected by currents or by the 



Fig. 5.— Isanomalies, compared with the mean Annual Temperature of 

 15° W., in corresponding latitudes. 



direct influence of the proximity of land. In the case of the meridian 

 of 15° W., we find that, until we approach Iceland, the mean tem- 

 perature falls in a smooth curve, very nearly in direct proportion 

 to the cosine of the latitude ; but in the neighbourhood of Iceland 

 we have a somewhat sudden and rapid fall. In short, our standard 

 of comparison becomes itself anomalous in the neighbourhood of 65° 

 N. lat. ; and accordingly our thermal anomaly in the North Sea and 



