APPENDIX. ALTITUDES DETERMINED IN ECUADOR. 395 



A._ALTITUDES DETERMINED IN ECUADOR. 



The heights entered in the tables at pp. 399-401, have been calculated ^ from 

 observations of Mercurial Barometers, unless the contrary is pointed out. 

 Three mercurials were taken to Ecuador, and were made for the journey 

 by Mr. J. J. Hicks, of Hatton Garden, London. Two of these (marked No. 

 550 and No. 558) were Mountain Barometers on Fortin's principle, and were 

 intended for use in the interior, No. 550 being graduated from 32*5 to 10 

 inches, and No. 558 from 33 "5 to 12 inches. The third barometer (No. 

 554) of the Kew pattern, was intended for employment at the level of the 

 sea, and was graduated from 32 to 27 inches. All three read to j^q of an 

 inch (0-002). 



After having been under examination by myself for some time, they were 

 sent to Kew Observatory for verification, and the certificates which were 

 given stated that the error of No. 550 was + 0-004, of No. 558 - 0-005, and 

 that No. 554 was free from error. These barometers remained in my hands 

 under constant examination and comparison until our departure. 



We arrived at Guayaquil on December 9th, 1879, and upon the 10th, 

 11th, and 12th I took two readings daily of the three mercurials for com- 

 parison against each other. The mean of the greatest differences between the 

 three instruments on these six occasions amounted to one-hundredth of an 

 inch (0-010). 



Mr. George Chambers, British Consul at Guayaquil, very kindly volun- 

 teered to read No, 554 during our absence in the interior ; and he did so at 

 11 A.M. and at 6 p.m., from December 1879 to July 1880.^ These hours 

 were considered by us to be the most likely ones at which we should be able 

 to observe simultaneously. 



Nos. 550 and 558 travelled in company as far as the Third Camp on 

 Chimborazo ; but after that time, as a general rule, I took No. 558 alone to 

 the greater heights, and left the other below, in reserve. No. 558 accom- 

 panied us everywhere, and consequently travelled more than No. 550, and 

 the latter more than No. 554 (left at Guayaquil), 



During our stay in the interior I compared the two mercurials against 

 each other upon all convenient occasions, and perceived a slight increase in 

 the difference of their readings. 



Upon return to Guayaquil, the increase was found to amount to 0*003 

 of an inch, having been 0-006 at the start, and 0-009 on return. These 

 two barometers were also compared (upon return to Guayaquil) against No. 



1 By Mr. William Ellis, F.R.A.S., of Greenwich Observatory. 



2 Mr. Chambers also read Aneroid No. 580 (which was left with him in case of acci- 

 dent to the mercurial barometer) throughout the same period. 



