198 Deleros on the Influence of the Time of the Day {[Marcu, 
In the first, divided into 14 columns, and which we are pre- 
vented from publishing by its great size, we find the dates (days 
and hours), the heights of the barometer observed, and the 
temperature of the mercury and the air at Lichtemberg ; the same 
elements for Strasburg; the numbers given by the tables of 
Oltmans ; the corrections for the temperature of the mercury 
and the air; for the Jatitude, for the diminution of gravity in the 
vertical; the difference between the heights of the barometers, 
derived from the calculation of each of the corresponding obser- 
vations ; and, finally, all the meteorological circumstances that 
accompanied each observation. This table contains all the 
elements of the second, the object of which is to show the 
influence of the time of the day, by the way. in which the results 
are grouped.’ This table accompanies the present article. Its 
eneral title, and that of its several columns, indicate sufficiently 
its object. We perceive the results of each observation grouped 
respectively into each of the horary epochs that furnished it : at 
the end of each observation is given, in metrés and centimetres, 
the quantity by which it differs from the true height of the 
station as determined geometrically. At the bottom of each of 
the five columns of these differences is given the mean number of 
metres round which the results oscillate; and the greater this 
number is, the ess is the time of the day which it represents 
favourable for accuracy. But by casting the eye over the bottom 
of the five columns, we shall perceive the results of which we 
form this very instructive little table. 
Hours of simultaneous Mean errors of the 
observation. results, 
Metres. 
8 a.m ee —3°58 
Ponds SroFierer sears Tee aa: of 110 observa- 
= “i Mee ioe _0:59 | ‘tons compared. 
Le LRG ESSAI ete 
That is to say, that if we choose eight in the morning for the 
simultaneous observations of two barometers placed as above 
stated, we have the mean chance of an error of 34 metres in the 
264; that is to say ,1,th of the whole; at noon the error is only 
0°62, or -4,, which is very small ; but at two o’clock, p. m. the 
error is still less, being only 0°59 in the 264 metres, or =4,. 
