344 



TRAVELS A3I0NOST THE GREAT ANDES, chap. xix. 



he was always laden with 12 J or 25 lbs. additional weight must 



be taken into account if com- 

 parisons are instituted with his 

 rates. The conservation of these 

 instruments occupied the first 

 place in the thoughts of every 

 one during the whole of the time 

 we were in the interior, as they 

 were the Standards upon which 

 everything depended. 



The comparisons of the Ane- 

 roid Barometers which were made 

 against the Mercurials whilst in the 

 field are given in Appendix C ; 

 but the account of the subsequent 

 investigations into the behaviour 

 of Aneroids in general extends to 

 too great length to be included in 

 this volume, and is rendered in the 

 pamphlet Hoiu to use the Aneroid 

 Barometer} 



JEAN-ANTOINE AND THE BABIES. 



1 The following is a recapitulation of the principal points which have come out 

 in the course of this enquiry. 



1. All aneroids lose upon the mercurial barometer when submitted to diminished 

 pressure. When diminished pressure is maintained continuously, the loss commonly 

 continues to augment during several weeks, and sometimes grows to a very import- 

 ant amount. The most important part of any loss that will occur will take place 

 in the first week. The loss which takes place in the first week is greater than in 

 any subsequent one. A considerable part of the loss which takes place in the first 

 week occurs in the first day. The loss may be traced in a single hour, and in 

 successive hours upon aneroids with expanded scales. The amount of the loss 

 which occurs is different in different instruments. The amount of the loss in any 

 aneroid depends (a) upon the duration of time it may experience diminished press- 

 ure, and (&) upon the extent of the reduction in pressure. 



2. When pressure is restored, all aneroids recover a portion of the loss which has 

 previously occurred; and some, in course of recovery, gain more than they have 



