482 REPORT—1862. 
Taste XI. (continued)—Comparison of the Readings of Mercurial and 
Aneroid Barometers and Negretti’s new Barometer, in the Ascent on 
September 5. 
. Excess of Reading above 
Readings of Barometers, | Excess of | | NOcteuti"a new Bavometer 
Month, day, hour Aneroid 
and minute. : above 
Negretti’s Siphon of of 
Siphon. | Aneroid. new Barometer. Siphon Aneroid 
Barometer. Barometer. | Barometer. 
hm |g] ‘in, in. in. in. in. 
Sept. 5, 0 © 0] 2940 29°40 pecans 0°00 
25) To) 23°97; 29°10 teseee +0'13 
g's gol "2857 28°60 28°72 +0'03 —O'rs 
rT 6 . ‘o) (28748 | 28°35 28°55 —0'03 —oO'17 
IIo o| 26°19 26°20 26°35 +oro1 —o'16 
I Ir 30] 25°49 W5*G2 al sees +013 
I 13 oO} 24°30 24°45 24°60 -+or1s —0°30 
I 14 30] 23°70 23°90 23°99 +0'20 —0'20 
© 16 0) ©23736 De Plo) | one +0'04, 
I 17 40| 22°66 22°71 22°75 +or05 —o'09 
TF 2x; of © 20°72 20°60 20°65 —o'l2 0°07 
122 0} 20°07 20°17 eoeeee -+o'1o 
I 25 30] 17°93 18°10 17°90 +017 +0'03 
127 oO} 16°94 16°90 16"90 0704 +0'04. 
I 28 o| 16°69 16°65 teeeee —0'04. 
135 oO} 14°65 14°90 sevece +0'25 
£20, oO} “F4°k5 T4780 | seeee . +o0'25 
I 37 30] 14°47 14°80 teeeee +0°33 
2 8 30] 12°55 12°80 speeae +0°25 
2 9 30| 16°37 16°45 16°50 +0'08 —0'13 
2 9 40! 17°07 seeeee 17°20 sectereee | —=O'TZ 
2.2% Gl & Wye MS Fess a aa lie eens toss | —O'L4 
2 16 10) 19°75 19°90 Tg"90 +or'1s —O'15 
2 16 20| 20°05 20°25 20°25 -+o'20 —0°20 
2 16 50} 20°65 20°65 20°70 o'00 —0'05 
@ 17 -gq|,) 21°15 21°55 21°30 -+o'40 —oO'ls 
2 19 30) 21°85 21°90 21°90 +0105 | —0'05 
2 ZO 1:20! 22°04. Sl. Hewes < ZOO 4 eae wwe | 40°04 
2 20 40] 22°24. 22°20 22°45 —o0'04, —o'21 
2 23 20) 22°64 22°76 22°70 +o12 —o0'06 
2 23 50) 22°93 | 23°20 23°00 +0'27 — 0°07 
224 O} 23°03 23°00 22°95 —0'03 +0'08 
2022 Ol) 25 Ao 25°55 25°30 tors -+o'1o 
2 38 of 26°40 26°35 26°35 —0'05 +0'05 
3 6 ° RPE 29°02 220! ws |) csneoaeset (| Senn dg etetr 
The numbers in the last column but two show the differences between the 
readings of the siphon and aneroid barometers, those in the last column 
but one the differences between the readings of the siphon barometer and - 
Negretti and Zambra’s new barometer, and those in the last column the 
differences between the readings of the aneroid barometer and Negretti and 
Zambra’s new barometer; these several differences are all small, and are 
within the probable error of observation, as it is not possible that the read- 
ings can be made at the same instant. They prove that all the observations 
made in the seyeral ascents may safely be depended upon, and also that an 
aneroid barometer can be made to read correctly to pressures below 12 inches. 
