410 COMPARISONS OF THE ANEROID BAROMETER, appendix. 



at Quito to the top of the hill called the Panecillo, on this occasion reading 

 the ' scales of feet ' upon them before departure, and again upon return to 

 Quito. From the means of the ascending and descending readings, the 

 summit of the Panecillo appears to be 651*25 feet above the level of the 

 principal Plaza of Quito, which from the mean of twenty-two observations of 

 mercurial barometer by myself is found to be 9343 "3 feet above the sea. I 

 have no observation of mercurial barometer on the Panecillo ; and, if I had, 

 should still quote by preference the independent observations of Messrs. 

 Reiss and Stiibel, who, from the mean of a large number of observations of 

 mercurial barometer, give for the height of Quito 9350 feet, and for the 

 Panecillo (two observations of m. b.) 10,007 feet. Their difference of level 

 therefore is 057 feet, or 5 feet 9 inches more than the height indicated by 

 the aneroids. 



Barometer. 



At Quito, in 

 Hotel. 



Summit of 

 Panecillo. 



= a rise of 



On return 

 to Quito. 



= a fall of 



Aneroid A 



10,080 feet 



11,325 feet 



645 feet 



10,760 feet 



565 feet 



do. B 



12,310 „ 



13,050 ,, 



740 „ 



12,390 „ 



660 „ 



do. D 



11,260 „ 



11,950 „ 



690 „ 



11,340 ,, 



610 „ 



do. E 



11,000 „ 



11,680 „ 



680 „ 



11,060 „ 



620 ,, 



Mean of ascending readings 688*75 feet. 

 Mean of descending do. 613*75 feet. 

 Mean of ascending and descending 651*25 feet. 



§ 16. As the journey approached its termination, I became curious to 

 observe how the aneroids would read against the mercurials upon return 

 to the level of the sea. We arrived at Guayaquil again on July 13, 1880, 

 and the barometers were compared against each other from the 16th to the 

 27th. ^ The error of aneroid A upon the 16th was — 0*361 of an inch, and 

 of E — 0*321, but by the 27th their respective errors diminished to — 0*341 

 and — 0*291. I have not allowed the index of either to be altered. They 

 continued to recover in the course of time ; and I found, upon January 9, 

 1885, that aneroid E possessed an index-error of +0*160, which was very 

 nearly its error upon the last comparison in 1879 before our start, when 

 it was seen to be + 0*182. Aneroid A did not recover with the same 

 rapidity. Upon January 9, 1885, its error had diminished to — 0*200, and 

 in fiv^e years more it recovered another tenth of an inch. 



§ XI. In the tables at pp. 414, 415, the comparisons of the aneroids A and E 

 are presented separated from the others. These two instruments were those 

 which were most consistent in their behaviour, and were those wnich were 

 most frequently employed. From inspection of the tables it will be immedi- 

 ately apparent that ' a good return ' is of little value as a test of working. 



1 See the tables at pp. 414, 415, for this and for the succeeding paragraph. 



