APPENDIX. C03IPARIS0NS OF THE ANEROID BAROMETER. 407 



§ 3. Comparisons were again made at Colon and Guayaquil, and at 

 neither of these places (at the level of the sea) was there any further in- 

 crease in the mean error of the aneroids ; but at Munapamba (where we 

 commenced to mount the Pacific range of Ecuador) their difference amongst 

 each other had risen to 0*500 of an inch, and the mean error was increased 

 to- 098 of an inch. 



§ 4. At Tambo Gobierno (the culminating point of the road over the 

 Pacific range of Ecuador), 10,417 feet above the sea, the mean error of the 

 aneroids had risen to — 487 of an inch, and the extreme difference of their 

 readings amounted to 0-715. 



§ 5. With the descent on the other side the aneroids came more closely 

 together, but their mean error continued to augment, — being upon arrival 

 at Guaranda- (8894 feet) -0-520, and it rose in one week to —0-655. 

 The ' greatest difference ' also continued to increase, and it stood on Christmas 

 Day at 0-800 of an inch. The following record showing the continual 

 increases in the errors, will be found interesting. 



No. of Barometer. 



Dec. 18, 1879. 



Dec. 20, 1879. 



Dec. 23, 1879. 



Dec. 25, 1879. 



Aneroid A 



21-700 



21-700 



21-700 



21-600 



B 



21-170 



20-960 



20-940 



20-870 



D 



21-460 



21-430 



21-450 



21-390 



E 



21-500 



21-500 



21-500 



21-440 



F 



21-220 



21-030 



20-950 



20-800 



G 



21-400 



21-380 



21-300 



21-300 



Extreme differences . . 



0-530 



0-740 



0-760 



0-800 



Mean of aneroids . . . 



21-408 



21-333 



21-321 



21-233 



Mean Merc. bar. 



21-928 



21-912 



21-934 



21-888 



Mean errors of aneroids . 



-0-520 



-0-579 



-0-613 



-0-655 



§ 6. Upon December 26, 1879. we encamped on the Arenal (14,375 

 feet), at the foot of Chimborazo, and on the morning of the 27th the mean 

 error of the aneroids was found to be —0-737, and their greatest difference 

 0-880. 



§ 7. We then moved up to the Second Camp on Chimborazo (16,664 

 feet , the mean error continuing to rise, and amounting upon December 30 

 to -0-903. 



§ 8. Upon arrival at the Third Camp (17,285 feet) I found that com- 

 parisons at greater heights would have to be made between five aneroids 



1 As aneroid 580 was left at Guayaquil, the comparisons are now between the seven 

 remaining instruments. 



2 Aneroid C was lost or stolen shortly before arrival at Guaranda, thus reducing the 

 number under comparison to six. 



