Sim-spots and Terrestrial Phenomena. 



231 



" Sun-spots and Terrestrial Phenomena. I. On the Variations of 

 the Daily Range of Atmospheric Temperature, as recorded 

 at the Colaba Observatory, Bombay." By Charles Cham- 

 bers, F.R.S., Superintendent. Received May 30. Read 

 June 15, 1882. 



The present investigation is on the model of one by Dr. Balfour 

 Stewart, published in the " Proc. Roy. Soc." (vol. 25, p. 577), and 

 dealing with similar records obtained at the Kew Observatory. The 

 records extend, in the present case, from June 1, 1847, to December 

 31, 1880, and consist of excesses of the highest temperature 

 observed above the lowest temperature observed on every observa- 

 tion day of the period, and all are therefore necessarily positive 

 numbers. Until the end of the year 1851, the observation day was 

 the Gottingen Astronomical day : since that time it has been the 

 Bombay Civil day. The daily excesses were obtained for the period 

 from 1847*42 to 1873'0, from hourly observations made on all days 

 except Sundays and a few holidays, and for the period from 1873*0 to 

 1881*0 from daily readings of self -registering maximum and mini- 

 mum thermometers taken on all days without exception ; for all days 

 previous to 1866*0 they are differences of uncorrected readings of the 

 dry-bulb thermometer, but for all later days every individual thermo- 

 meter reading was corrected for the error of graduation of the 

 thermometer before the differences were taken. The maximum 

 thermometer is a mercurial one of the construction known as Negretti 

 arid Zambra's: the minimum is a spirit thermometer, of which the 

 chamber at the top of the tube is bent upward, so as to prevent the 

 accumulation in it of condensed spirit ; the instrument was tested in 

 1865, and again in 1881, and it was found on the latter occasion to 

 have practically the same error as before. The dry bulbs (up to 

 1873*0) were mercurial thermometers by Newman, with scales 

 divided to fifths of a degree. 



A. Annual Variation of Temperature-Range. 

 B. Variation of Long Period. 



2. Table I exhibits the monthly and annual means of the daily 

 temperature-range. 



Changes were made in the mode of exposure of the thermometers, 

 of a character likely to affect the comparability of the preceding and 

 following observations, in 1851 and again on 1866*0 ; but the annual 

 means in the following table seem to imply that the state of things 

 holding in 1851 was maintained for some time longer, and as the only 

 event on record that would suggest a definite limit to that time is a 

 change of thermometers on the 31st March, 1852, we have divided the 



vol. xxxiv. R 



