Observations with Baroiiieters and TJierniojuetcrs. 171 



3rd. A \\ inch Aneroid, marked "Compensated, Kilpatrick k 

 Co., London," graduated to 0-05 inch and easily read to O'Ol 

 inch. This Aneroid was made by Barker k Co., of London. 



The Aneroids, 1, 2 and 3, were altered by having a disk fixed 

 to the end of the index and perpendicular to the plane of the dial 

 for the purpose of eliminating parallax as suggested by Admiral 

 Wharton in his " Hydrographical Surveying." 



4th. A Mountain Mercurial barometer of the Gay Lussac 

 syphon type, with verniers reading to O'OOl inch. The frame 

 is marked Troughton k Simms, London, and the tube was made 

 and filled by Yeates of Melboui'ne in December, 1894. The 

 external diameter of the tube is 0-25 inch, and probable 

 intei-nal diameter 0-15 inch. A similar tube was in the frame 

 when obtained by the writer, though, probably, that originally 

 issued with it was larger. Its external diameter cannot however 

 have exceeded O'oO inch in any part, and portions of it must 

 have been much less. The attached thermometer is fixed to the 

 middle of the frame, and the outer portion of the bull) is exposed. 



5th. A Boiling-point thermometer, marked 1,013,848, 

 Kilpatrick k Co., Hicks' patent fixed zei'o K, C, 95, and 

 graduated on stem from 193° to 2 13° -5 Fahr., the divisions 

 being to 0°-05, and the length of the graduations 18| 

 inch. The bore of the tube is fairly fine, and the external 

 dimensions of the bulb are: length 2*25 inches, diameter 0'3 

 inch. The total length of the thermometer (which was made 

 l)y Hicks) is 23 "5 inches. It was placed in a steam jacketed 

 tube attached to a copper boiler, and the distance from the 

 bottom of the bullj to the water-level was never less than 5 

 inches. When the observations were in progress a glass tube 

 manometer, filled with water, was attached to the apparatus 

 at the level of the bulb, but the pressure indicated never 

 exceeded 0-003 inch of mercury. During each boiling-point 

 observation about two cubic inches of water were evaporated, 

 and care was taken to have a considerable quantity of water 

 left in the boiler. 



The Observatory tests of the aneroids and boiling-point 

 thermometer are given in Appenchx A. 



The results of every observation taken are given in the 

 Appendix B. It will be noticed that the W^atkin aneroid 



