1890.] Temperature of the British Isles, 18 fi9— 1883. 303 



Simon (Sir J.), F.R.S. English Sanitary Institutions. 8vo. London 

 1890. The Anthor. 



Soret (J. L.), and A. Rilliet. Recherches sur 1' Absorption des 

 Rayons Ultra-Violets par Diverses Substances. Sixieme 

 Memoire. 8vo. Geneve 1890. The Authors. 



March 27, 1890. 



Sir G. GABRIEL STOKES, Bart., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : — 



I. "On Black Soap Films." By A. W. Reinold, M.A., F.R.S., 

 and A. W. Rucker, M.A., F.R.S. Received March 1, 1890. 



[Publication deferred.] 



II. " The Variability of the Temperature of the British Isles, 

 1869—1883, inclusive." By Robert H. Soott, F.R.S. 

 Received March 3, 1890. 



[Plate 9.] 



The mean diurnal variability of temperature has been the subject 

 of several papers which ha\e appeared in the * Zeitschrift der Oest. 

 Gesells. fur Meteorologie,' and elsewhere. Of these the most im- 

 portant is that by Dr. Julius Hann, entitled " Untersuchungen iiber 

 die Veranderlichkeit der Tagestemperatur."* This paper contained, 

 for ninety stations, distributed over the earth's surface, the mean 

 diurnal variability of temperature — that is, the mean difference of the 

 temperature of each day from tha t of the next — and also the frequency 

 of a variation of 2° C, 4° C, 6° C, &c, in each month. Dr. Hann 

 also investigated for a few stations the probability of a change of 

 2° C. and of 4° C. 



. In the case of some of the stations taken by Dr. Hann the figures 

 compared were not daily means, but actual readings at corresponding 

 hoars on successive days. In such cases the results for variability 



* 1 Sitzungsbeiichte der K. Akad. der Wiss. in Wien,' vol. 71, 1875. 



