482 Dr. W. A. Miller on a Self-registering Thermometer [June 17, 



have tabulated, these storms appear to be about half as frequent only at 

 the beginning as at the end of the south-west monsoon* 



It is probable that in the course of a few years, if not already, the obser- 

 vations of currents and sea temperatures, collected by the Meteorological 

 Department of the Board of Trade, will afford data for a satisfactory dis- 

 cussion of this subject, which is one of great importance to the compre- 

 hension of the meteorology of the Bay. 



Postscript. Received June 29, 1869*. 

 Since the above was written, I have visited Chittagong, and have found 

 that the elevation of the barometer-cistern at that place above sea-level 

 (which had been reported as 166*46 feet) is actually about 108 ft. only. 

 This correction requires an alteration of the reduced barometric pressures 

 for Chittagong (given on p. 473), which will consequently stand as fol- 

 lows : — 



23rd. 24th. 25th. 26th. 27th. 



Chittagong .. 29-906 29 913 29*949 29*8/3 29*894 



A few corrections must also be made in the text. The excess of pressure 

 at Chittagong, as compared with certain other stations on the 23rd and 

 25th, disappears, and on the 26th and 27th the noon pressure at this 

 place becomes lower than at any other station. The conclusions arrived at 

 in the foregoing paper are, however, unaffected by the correction. 



III. " Note upon a Self-registering* Thermometer adapted to 

 Deep-sea Soundings/' By W. A. Miller, M.D., Treas. and 

 V.P.R.S. Received June 3, 1869. 



The Fellows of the Royal Society are already aware that the Admiralty, 

 at the request of the Council of the Society, have placed a surveying-ves- 

 sel at the disposal of Dr. Carpenter and his coadjutors for some weeks 

 during the present summer, to enable them to institute certain scientific 

 inquiries in the North Sea. Among the objects which the expedition has 

 in view is the determination of deep-sea temperatures. 



Now it is well known that self-registering thermometers of the ordinary 

 construction are liable to error when sunk to considerable depths in water, 

 in consequence of the diminution produced for the time in the capacity of 

 the bulb under the increased pressure to which it is subjected. The index, 

 from this cause, is carried forward beyond the point due to the effect of mere 

 temperature, and the records furnished by the instrument rise too highf. 



A simple expedient occurred to me as being likely to remove the difn- 



* A chart, with wind arrows, showing the limits of the cyclone, accompanies the 

 paper, and is preserved for reference in the Archives of the Society. 



t In eca-waterof sp.gr. 1*027, the pressure in descending increases at the rate of 

 280 lbs. vpoa the square inch for every 100 fathoms, or exactly one ton for every 800 

 fathoms. 



