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1. For the derivation of the temperature of the clock 1 had the 
following data at my disposal. 
From 1862 to 1866 May a thermometer hanging at the pier of 
the clock was read at 8h 30m in the morning. 
Beginning from that time two thermometers suspended in the clock 
ease were regularly read, but from 1866 June to 1873 June these 
readings were only made at 8" 30" in the morning. Since 1873 July 
both thermometers were read five times a day. 
From July 1873 it was possible therefore to take daily means of 
the temperature according to the upper thermometer in the clock 
case in the same way as was done for the time after 1877. 
For former periods I had to find corrections in order to reduce to 
daily means of the latter thermometer. 
For the purpose of finding these corrections I compared: 
1st. For the years 1871, 1872 and 1873 the readings at 8" 30m in 
the morning of the upper thermometer in the clock case with those of 
the thermometer at the clockpier ; 
Ind, for the years 1873-—75 the readings at 8" in the morning 
of the upper thermometer in the clock case with their daily means. 
From the two comparisons [ found the following monthly means 
of the differences 4, — clock case — pier and 4, = daily means — 
readings at 8", everything being expressed in degrees RÉAUMUR. 
The index-corrections have been taken into account. 
LS Bs, A, Ap 
Jan. + 0.21 + 0.22 July + 0.01 + 0.36 
Febr. ili wis) Aug. ake) Al 
March ‚14 ‚44 Sept. 16 46 
April 5 ‚48 Oct. „20 ‚26 
May 06 38 Nov. 16 29 
June ‚03 47 Dec. 16 O4 
For all the months I adopted for A, the general mean — 0,15. 
For A, I adopted 
October—February + 0.20 
March—September -+ 0.45 
With the aid of these values and of the index-errors determined 
at regular intervals the necessary reductions were applied. 
Lastly I compared the temperatures according to the upper and 
lower thermometer, as has been done for the subsequent period, 
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