On the Surface Temperature of North Sea and North Atlantic. 31 



Looking in the first place at the former series, we see that in 

 20° W. and from ahout 45° N. to nearly 65° X. (that is to say, north- 

 wards to the coast of Icehmd) we have a beantifuUy simple and 



Fig. 25. — Surface-temperature fluctuations throughout the year, 

 along the meridian of 20° W. longitude. 



regular series of temperature phenomena (Fig. 25). We see at a 

 glance the following features: (1) The contour-line for each degree 

 centigrade forms approximately a sine-curve, with its summer 

 maximum to the northward, and its winter or spring minimum to 



