110 REPORT—1845. 
greater than at Senftenberg, a difference so small that no conclusion ean by 
it be arrived at to determine at which of the two stations it was greater. 
It may thus be concluded that the deviation of the curves from parallelism 
is produced by the difference in time at which the maximum and minimum 
took place at the two stations. By a closer inspection of the curves, it ap- 
pears that when they are either approaching to or receding from each other, 
this is produced by a minimum which has taken place sooner at Prague than 
Senftenberg. Thus the first curve on the 18th and 19th of June at Prague 
shows a minimum between the hours nineteen and twenty, whilst in the 
Senftenberg curve it is not perceptible till the hours of twenty-two to twenty- 
three, This fact becomes still more conspicuous on other days, for on the 
24th and 25th of August, where a minimum occurs in Prague at 4 o'clock, 
and at Senftenberg only at 10 o'clock, on the 29th and 30th of September we 
find the minimum at Prague already at the eleventh hour, which was only 
reached at Senftenberg on the nineteenth hour. Further, Oct. 3 and 4, 
minimum at Prague at the fifteenth hour, at Senftenberg at the sixteenth 
hour; Oct. 7 and 8, minimum at Prague at the second hour, at Senftenberg 
at the fifth hour ; Nov. 8 and 9, minimum at Prague at the seventeenth hour 
forty-five minutes, at Senftenberg at the nineteenth hour ; Nov. 13 and 14, 
minimum at Prague at the twelfth hour, at Senftenberg at the thirteenth 
hour; and Nov. 15 and 16, minimum at Prague at the sixteenth hour, at 
Senftenberg at the twenty-second hour. [The curves for the 18—19th June, 
24-95th June, and 25th—26th June, are given in Plate II. as examples. ] 
These facts have recurred so regularly, that although the number of ob- 
servations is not great, the law may be established between the above-named 
two places of observation with a degree of certainty the more to be relied on, 
as it invariably takes place whatever the direction of the wind may be. It 
thus follows that it has its crigin in the higher regions, and is independent of 
local influences. A change in the opposite direction, that is, a transition from 
rising to falling, does not appear greatly to affect the parallelism of the curves ; 
at all events no decisive proofs to that effect can be traced from the maxima 
of Sept. 30 and Oct. 1, Oct. 3 and 4, Oct. 4 and 5, Oct.6 and 7, Oct. 7 and 8, 
Oct. 14 and 15, and Nov. 15 and 16. 
But it is not only the minima terminating a long-continued decrease of a 
curve that follow the above-mentioned law, but also disturbances that hitherto 
have been considered as proceeding from local causes, such as transient gales 
of wind, thunder-storms, sudden changes of temperature and moisture, all 
which are indicated earlier at Prague than at Senftenberg by the autographs. 
It must however be owned, that the number of such eases hitherto observed 
is too small to draw certain inferences from. As an instance, the barome- 
tric curve at Prague on the 24th and 25th of June shows between the hours 
twenty and twenty-one a sudden transitory increase of pressure of the air, oc- 
casioned by a storm which came from the west-north-west wheeling round toa 
breeze from the east-north-east. The barometer at Senftenberg did not begin 
to rise before the twenty-first hour and thirty minutes, and continued to do 
so till the twenty-third hour, the wind at east-south-east. On the following 
day both places were visited by thunder-storms, which greatly affected the 
state of the barometer, causing it alternately to rise and fall. At Prague 
the first indications in the curve were perceptible at 7 o'clock, and the undu- 
lations extended to 10 o’clock. The phenomenon occupied the southern part 
of the hemisphere, the wind at south-west. In Senftenberg the thunder- 
storm lasted from 9 till 11, and at 9 o’clock the wind was north-west. On 
the 27th of June the thermometrograph at Prague indicated a rapid decrease 
of temperature between 3 and 4 o’clock, which was also perceived at Senf- 
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