Proceedings of the Royal Society of Victoria. 155 



The chair having been vacated by the President in ftivour 

 of the Vice-President, Mr. White. 



Professor Kerxot read a paper on the "Barometric 

 Measurement of Heights," giving the results of measure- 

 ments taken on a recent trip. 



Mr. Ellery said that the subject of the Barometric 

 Measurement of Height, was one in which all engineers 

 and surveyors must be interested. So for as his experience 

 went, a well made aneroid barometer was an extremely 

 useful instrument. Those who claim for the aneroid 

 barometer more perhaps than it deserves, must recollect that 

 they have not an easy thing to measure in weighing the 

 atmosphere. If people would only look at the w^eather 

 chart sent out from the Observatory every day, they would 

 come to the conclusion that this was true. Thus, in taking 

 a line with the mercurial barometer from the Observatory to 

 Gabo Island, it is found that in certain spots incorrect 

 readings are obtained. There are certain spots where there 

 is a depression in the atmosphere. Professor Kernot had 

 told them that he took readings from his barometer while 

 the train waited a few seconds at the different w^ayside 

 stations. Such readings were invariably incorrect. It 

 takes some time before the aneroid gets right after the 

 motion of the train. It must be read, to get correct 

 readings, some minutes after the train has stopped. 

 Another thing, in the small barometers, ten feet were 

 represented b}^ a hundredth part of an inch, and as such, 

 were not an easy thing to read. The greatest defect in 

 these aneroids lay in the want of knowledge of the 

 conditions of the atmosphere at the points of observation. 

 But even at best, the results to be gained w^ere merely 

 approximate. 



Mr. Allex said that so for as his experience went, the 

 aneroid barometer was perfectly useless, except when the 

 weather was favourable. He had recently made experi- 

 ments with one of Watkin's best instruments, one of 

 Mason's No. 1, and another of Watkin's No. 2. He tried to 

 take the height of a mantelpiece from the tloor. The first 

 result w-as, that Mason's gave 13 feet; Watkin's No. 1, 

 7 feet ; and Watkin's No. 2, 3 feet. He next raised the 

 instrument, with the result that in Mason's tliere was no 

 difference ; Watkin's No. 1, no difference ; Watkin's No. 2, 

 2 feet. 



