170 Proceedings of the Royal Society of Victoria. 



or lowerinf^ it, and the graduated scale by means of an adjusting 

 screw instead of by altering the level of the mercury in the 

 cistern as in the instruments of a more recent type. The 

 attached . thermometer is placed opposite the graduated scale at 

 the upper end of the tube which is the only portion exposed. 

 The distance from the thermometer bulb to the tube is y\ inch. 

 The instrument is one of those used in connection with Professor 

 Neumayer's Meteorological Investigations in Victoria, and reads 

 l)y vernier to 0"002 inch, and by estimation to 0*001 inch. 

 The vacuum appeal's to be good. There is little doubt that the 

 attached thermometer is more rapidly affected by variations of 

 temperature than the mercury in the tube, and hence that the 

 correction for temperature applied may at times have been 

 incorrect to the extent of, say, 0-005 inch as a maximum 

 (equivalent to a temperature error of 2 deg.). Probably the 

 maximum reading error did not exceed 0'004 inch, and the 

 writer is of opinion that differences of pressure as indicated by 

 this barometer miglit be relied on to about 0"00G inch. The 

 writer had not the opportunity of investigating for himself the 

 correction for index error, nor did it seem necessary, as it would 

 equally affect the whole of the observations and leave the 

 differences unaltered. 



No correction was applied for capillary depression, but the 

 height of meniscus was measured several times and found to 

 vary from 0"051 inch to 0"040 inch, corresponding to varia- 

 tions in the capillary depression of 0*002 inch, according to 

 Guyot's Tables, page 340. 



The instruments compared with the Standard barometer were 

 as follows : — 



1st. A Watkin 4.', inches Patent Aneroid, marked "Jewelled 

 and Compensated, No. 161, Kilpatrick k Co., London and 

 Melbourne." This instrument is graduated to 0-01 inch and 

 can easily be read to 0"002 inch. It was made by Hicks, of 

 London, and is the property of the JNIelbourne University. 



2nd. A 2. \ inches Aneroid, marked "Jewelled and Compen- 

 sated, Kilpatrick & Co., London and ^Melbourne," and graduated 

 to 0'05 inch and easily read to 0*01 inch. This aneroid was 

 made by Short it iNIason. 



