CHAP. XII. ECCENTRICITIES OF THE ANEROIDS. 221 



Or the matter may be put in the following way. When we 

 were at the bottom of the ravine, and the mercurial barometer 

 Xo. 558 read 23 '929 inches, the barometer at Guayaquil was 

 standing at 29*900 inches. The actual difference in the atmos- 

 pheric pressure between the upper and lower station was there- 

 fore 5*971 inches. Aneroid B, however, at the bottom of the 

 ravine, read 22*200 inches, and thus made it appear that there 

 was a difference of pressure of 7*700 inches. The error therefore 

 of B in a measurement of 5*971 inches was 1*729 inches, or 

 more than 28 per cent. Yet this same instrument, it was seen 

 just now, in a measurement of 2*237 inches, differed only to 

 the extent of 0*023 of an inch from the mercurial barometer. 

 Comparisons of this nature were continued, though no more are 

 quoted in the course of my narrative. I returned to England, 

 and remained for several years, entirely unable to understand 

 this anomalous behaviour.^ 



We stopped for the night at the village of Guallabamba 

 (7133 feet), a pleasant little place, with an agreeable tempera- 

 ture,^ embowered in foliage, where we bought oranges shaken 



1 It appeared inexplicable to several of the leading instrument-makers and 

 meteorologists under whose notice it was brought. The prominent manner in 

 which it was referred to in a paper communicated to the Royal Geographical 

 Society (see Proc. Roy. Geog. Soc, 1881, p. 450) also failed to draw elucidations 

 from any one. 



1 coutmued to investigate the matter ; and, after working during several years 

 in tabulating and comparing the original observations, subsequently occupied several 

 years more in experiments in the workshop, with the results which will be found 

 in the pamphlet entitled How to use the Aneroid Barometer. See also Appendix C. 



As even a condensed summary of this investigation necessarily extends to 

 considerable length, I have thought it best to issue it separately from, though 

 simultaneously with the present volume. 



2 At 8 p.m., 67° Faht. Strangers seldom come here. The natives said it was 

 two years since they had seen a gringo. The place was badly o£E for food. There 

 was of course no meat. Bread only came once a week from Quito. 



At the bottom of the Ravine of Guallabamba, at 2.30 p.m., temperature in 

 the shade was 75°-5 Faht., and this was the highest we experienced in the shade 

 anywhere in the interior of Ecuador. 



