72 Proceedings of the Royal Society of Victoria. 



the records, but I give those I have been able to find. On 

 March 21, 1883, I measured the heights of the following 

 stations on the Sandhurst line, with the French barometer 

 mentioned above. I left Melbourne at G.45 a.m., the 

 barometer reading 775 millimetres, and temperature of the 

 air 20° centigrade. When I reached Kangaroo Flat at 10.46 

 a.m. the barometer read 748 millimetres, and the tempera- 

 ture of the air was 24 6° centigrade. The following are the 

 corrections in feet to be applied to the aneriod heights to get 

 the true heights : Sunbury + 26, Lancefield Junction + 

 105, Gisborne + 50, Macedon — 9, Woodend + 96, Malms- 

 bury — 48, Taradale + 12, Castlemaine + 34, Kangaroo 

 Flat — 34. On May 8 of the present year, I took No. 3 of 

 the above-mentioned barometers along part of the same line. 

 I started at 7 a.m., the barometer reading 30'30 in., and the 

 temperature of the air being 58° Fahr. I reached Macedon 

 at 8.45 ; the barometer reading 28-73, and the temperature 

 of the air 66°. I left Macedon at 5.30 p.m.; barometer 

 28'65, air 66°, and arrived in Melbourne about 7 p.m. ; 

 barometer 30'28, air 62°. Most of my levelling this day was 

 done oft' the railway, where I had no levels for comparit^on, 

 but the known heights mea,sured required the following- 

 corrections : Gisborne + 154, Macedon (from up readings) 

 + 151, and from the return readings + 86. The above 

 results are not given as specimens of the best method of 

 using the aneroid, but the observations were made with the 

 greatest care. When the mercurial barometer is used, and 

 the stations are in the same vertical, where the error of 

 gi-adient should be very little, the errors are generally 

 greater than expected. One of the most extensive series of 

 this descri]3tion was carried out from Jul}" 22 to October ] 5, 

 1848, by the Royal Engineers employed in the trigono- 

 metrical survey of Great Britain. Four mercurial bai-o- 

 meters were used, two of these were placed on the top of the 

 dome of St. Paul's Cathedral in London, the other two rested 

 on the floor under the centre of the dome ; after 62 observa- 

 tions had been taken the barometers were transposed, and 89 

 additional observations were made. The mean of the first 

 set made the height 35699 feet, and the mean of the second 

 set 353-57, whereas the actual height was 352-75 ; both 

 determinations were therefore in excess of the real amount 

 — the first to the extent of 4*24 feet, and the second to 0-82 

 feet. Most mountain aneroids are furnished wdth an 

 altitude scale, either on the same dial as the inch divisions 



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