144 APPENDIX. 



Meteorological observations, made, in various countries, on the 

 earth's surface. No opportunity ought therefore to be lost in 

 making these observations. The instruments required for 

 observing the Meteorological phenomena of any climate, are, 

 The Portable or Adie's Patent Sympiesometer, the Thermo- 

 meter, Hygrometer, and Compass. The former instrument 

 is used to determine the pressure of the atmosphere, the 

 altitude of any situation above another, or above the level 

 of the sea. To obtain the altitudes from the Barometer, ob- 

 servation tables are required. The Sympiesometer gives the 

 altitudes, without the use of tables, and only requires a single 

 process of subtraction and multiplication. 



Besides the common use of the Thermometer, namely to 

 ascertain the temperature of the air, it may be used for finding 

 the temperature of springs, &c., from which a knowledge of 

 the heights may be deduced. 



The Reflecting Compass is a very useful instrument to tra- 

 vellers. With this instrument the variations of the magnetic 

 needle may be found, at any part of the globe, and the relative 

 position of objects determined. 



LIST OF INSTRUMENTS USED BY NATURALISTS 

 AND TRAVELLERS. 



Made and sold by Mr Alexander Adie, Optician and Ma- 

 thematical Instrument Maker to the King, No. 58, Princes' 

 Street, Edinburgh. 



ABIE'S 'BAROMETER OR SYMPIESOMETER, for measuring heights 



&c., from 3 3s. to 12 12s. 

 THERMOMETERS, from 8s. to 18s. 

 HYGROMETERS, or DEW POINT instrument, from 1 5s. to 



2 2s. 

 KLINOMETERS, for finding the dip of stratified rocks, from 



1.0s. 6d. to 3 3s. 



PHOTOMETERS, from ,1 Is. to 2 2s. 

 The COMPASS Box, from 3s. 6d. to 10s. 

 The REFLECTING COMPASS, from 2 2s. to 2 12s. 6d. 



