962 



NewmarC% improved Portable Barometer^ ^c. [No. 1 20. 



of the mercurial column, and that the daily means combine the errors 

 or personal equations of the different observers. It is perhaps super- 

 fluous to mention, that the first comparative reading of each portable 

 Barometer has been taken as a Zero, to which all the corrections for 

 capacity have been made, and if the instrument could be read with 

 precision, all the differences from the standard should have come out 

 alike. The differences of the partial results from the final mean 

 are, however, generally within the limits of the probable error of obser- 

 vation, and the latter may therefore be considered as correct an ap- 

 proximation as could, under the circumstances of the comparison, be 

 obtained, and certainly sufficiently so to warrant the use of the instru- 

 ment in the determination of altitudes, comparatively with the Observa- 

 tory standard, to which, provided the cisterns remain mercury-tight, 

 they will now be immediately applied. The results of those observa- 

 tions will be communicated hereafter. 



Table of the mean daily comparisons of Portable Barometers, Nos. 40 

 and 44, with the Observatory standard, No. 40. 





Standard. 





Portable Barometer No 



40. 





1 



Portable Barometer No 



.44 

















t? 1 v,_- 



tJ I c 







*^ 



>- . 



, 



a 



1 



ill 



1 







1- 



U 



11 



II 







1« 



is 



o & 



11. 



1 



II 













s 



O o 



1 



Q 







'^ 



u s 



6 



S 







23-336 







23-306 



















—•030 



23^343 

















+•007 



1 



23-315 



61-6 



23271 



61-9 



— -037 



-•009 



23 260 



-•052 



23-324 





—•010 



-•004 



23^320 





-•004 



2 





357 



62- 





316 



62 1 



-j-010 



H-002 





318 



— 



041 



•365 





+ 



•022 



+ 



•004 





369 





-012 



3 





S33 



62-1 





2-89 



62-3 



—•017 



-•004 





285 



. — 



048 



•335 







■008 





•002 





333 





-•000 



4 





339 



62-6 





300 



63-0 



—•006 



— 001 





299 



— 



038 



•346 





+ 



•003 



+ 



•001 





347 





-•006 



6 





308 



61-7 





272 



62 



— -034 



—•008 





264 



— 



044 



•316 







•027 





•005 





311 





-•003 



6 





261 



61-3 





220 



61-5 



—086 



—.027 





193 



— 



068 



•264 







•079 



_ 



•014 





250 



— 



-Oil 



7 





285 



60-7 





232 



61-3 



—•074 



—•018 





214 



— 



071 



•289 









■054 







•010 





279 





-•006 



8 





394 



60-1 





348 



60-5 



-f-042 



-[-•010 





358 



— 



046 



•396 







•053 



-. 



•010 





406 



H 



-•014 



9 





404 



60- 





354 



602 



+•048 



-1-012 





366 



— 



028 



•407 







•064 



-. 



•012 





419 



-i 



-•015 



10 





386 



59-7 





347 



601 



--041 



-[-•010 





357 







029 



•394 







•051 





■010 





404 





-018 



11 





386 



58-9 





348 



58-7 



--042 



--•010 





358 



_ 



029 



•398 







•055 



-. 



•010 





408 





■•022 



12 





429 



57-3 





380 



57-0 



- --074 



4-018 





398 



— 



031 



•432 





"■ 



•089 



-- 



■016 





448 



- 



-019 



13 





399 



56-9 





353 



56-5 



--•047 



-foil 





•364 







035 



•412 







•069 





•013 





425 





-026 



14 





354 



57-3 





306 



57-1 



- --000 



-I--00O 





306 



— 



048 



•364 







•021 





•004 





368 





■014 



15 





408 



58- 





362,57-71 



- --056 



--•013 





375 



_ 



033 



•418 







•075 



.- 



•014 





432 





-•024 



16 





388 



58-7 





335 



58-2 



--•029 



-j-007 





342 



— 



046 



-394 







•051 



+ 



•010 



•404 





••016 



17 





346 



59-4 





296 



59-1 



— 010 



—002 





294 



— 



052 















18 





320 



59-4 





280 



59-3 



—•026 



— O06 





274 



_ 



046 















19 



•362 



59-2 



•318 



59-3 



-I-012 



-f-003 



•321 



—•041 













2_ 



mean 



23-356 



59-8 



23-312 



69-9 



^.•O06 



-f-001 



23^313 



— •043 



23-366 





+ 026 



+ •004 



23^370 



+ 011 



Magnetic Observatory, Simlah, bth Nov. 1841. 



* tKis difference is taken from the mean of the standard for 16 days, viz. 23.359 inches. 



