1903-4.] Prof. C. G. Knott on Ocean Temperatures , etc. 173 
Ocean Temperatures and Solar Radiation. 
By Professor C. G. Knott. 
(Read February 15, 1904.) 
Two years ago I communicated a short paper on Solar Radia- 
tion and Earth Temperatures ( Proc ., vol. xxiii., pp. 296-311). 
This paper had its origin in a critical discussion of certain results 
deduced by Dr Buchan from observations of Mediterranean tem- 
peratures which had been made by the staff of the Austrian war- 
ship Pola. The mathematical method by which I discussed the 
relation between the solar energy incident on the surface of earth 
or sea, and the corresponding fluctuations of temperature in the 
rock of the Calton Hill and the surface waters of the Mediter- 
ranean, has attracted some attention in America ; and correspondence 
with Professor Cleveland Abbe has drawn my attention again to 
the subject. In this paper I propose to consider more carefully the 
significance of the observations made and published by the Austrians. 
These are contained in four quarto volumes, which Dr Buchan has 
kindly placed in my hands for the purposes of a thorough investi- 
gation from the point of view of solar radiation. Dr Buchan 
clearly saw that something might be made out of these ; and the 
results he gave two and a half years ago before the Society indi- 
cated a penetration of solar heat every day to a depth of more 
than 100 feet. The results were based upon means of tempera- 
ture at different depths grouped according to the time of day at 
which they were taken. As I showed in my former paper, the 
results so deduced indicated a daily penetration into the waters of 
the Mediterranean of an amount of heat greater than the sun 
could supply. 
From the point of view of the present inquiry, the method 
adopted by the Austrian observers is not altogether satisfactory. 
Their immediate object seemed to have been to accumulate a 
sufficient number of temperature and salinity observations at 
various depths and at various stations, so as to enable them to 
draw isotherms and lines of equal salinity at different depths in 
