J 830.] 
On the mean Temperature of Calcutta 
287 
7/1 
n 
The mercury, in passing from the maximum to the minimum, proceeds without 
any sudden start, with a motion gradually accelerated, for the first half of the 
range, and then it decreases, in like manner, during the remaining half, as may 
be represented in the accompanying figure. 
The intervals of maximum 
W 71 
and minimum, being gene- 
rally six hours, the mean 
height will occur about the 
middle of the tide, or about 
3 hours from each ; now, 
without enquiring particularly into the nature of the curve, we may find the ordinate 
n. y. corresponding to in. n. by a property common to all curves of finite curvature 
near the point of contact, viz. that the deflection is as the square of the largest, 
that is, ny. is as mn. 2 . Strictly speaking, this'is the equation to the parabola ; 
but the whole variation is so small, that the ordinates would not sensibly differ 
from those of any curve of the second order. 
The table may be useful to those observers, who, in travelling, are frequently 
obliged to make their observations without waiting for the maximum or minimum. 
R. S. 
Table of the difference of the Barometer, from the Maximum or Minimum, for every 
quarter of an hour of the tide. 
.2 
Distance from the time of Maximum ^ or Minimum 
• 
c 
o 
,5 •i 
m 
m 
in 
h m 
h m 
h m 
h m 
h m 
h m 
h in 
li m 
1 hm 
ci 7^ 
> 0 
15 
30 
45 
1.0 
1.15 
1.30 
1.45 
2.0 
2-15 
2-30 
2 45 
30 
*■-+- 
c 
•01 
•0000 
•0001 
•000 
.000 
•001 
•002 
•002 
•002 
.003 
•003 
•004 
•005 
•01 
•02 
•0001 
•0003 
•001 
•001 
•002 
•002 
•003 
•004 
.006 
•007 
•008 
•010 
•02 
■OS 
•0001 
•0004 
-001 
•002 
*003 
•004 
•005 
•007 
.008 
•010 
•013 
•015 
•03 
•04 
•0001 
•0006 
•001 
•002 
•003 
•005 
•007 
•009 
.011 
•014 
•016 
•020 
•04 
•05 
•0002 
•0007 
•002 
•003 
004 
•006 
•008 
•Oil 
.014 
•017 
•021 
•025 
'05 
•06 
•0002 
•0008 
•002 
•003 
•005 
•007 
•010 
*013 
.017 
•021 
•025 
•030 
•06 
•07 
•0002 
•0010 
•002 
•004 
•006 
•009 
•012 
•016 
.020 
•024 
•029 
•035 
•07 
•08 
•0003 
•0011 
•002 
•004 
•007 
•010 
•014 
•018 
.022 
•028 
•033 
•040 
•08 
• 0 !) 
■0003 
•0012 
•003 
■005 
•008 
•011 
•015 
•020 
.025 
•031 
■038 
•045 
•09 
•10 
•0003 
■0014 
•003 
•005 
•009 
•012 
•017 
•022 
.028 
•035 
•042 
.050 
•10 
•11 
• 0004 
•0015 
•004 
•006 
•009 
•014 
•019 
•024 
•031 
.038 
•046 
•055 
•11 
-12 
•0004 
•0017 
•004 
•007 
•010 
•015 
•020 
•027 
•034 
.042 
•050 
•060 
•12 
•IS 
•0005 
•0018 
-004 
•007 
•Oil 
■016 
‘022 
•029 
•036 
.045 
•054 
■065 
•13 
•14 
•0005 
•0019 
•004 
•008 
•012 
•017 
•024 
•031 
•039 
.048 
•059 
•070 
•14 
•15 
•0005 
•0021 
•005 
•008 
•013 
•019 
•026 
•033 
•042 
.052 
•063 
075 
•15 
■Hi 
0000 
•0022 
•005 
•009 
•014 
•020 
•028 
•035 
•045 
•055 
•067 
•080 
•16 
•17 
•0006 
•0024 
•005 
•009 
•015 
•021 
•029 
•038 
•048 
•059 
•071 
•085 
•17 
•18 
•0006 
•0025 
•006 
•010 
•016 
•022 
•031 
•040 
■050 
•062 
•076 
*090 
•18 
•19 
•0007 
•0026 
•006 
•Oil 
•016 
•024 
•032 
•042 
•053 
•066 
•080 
•095 
•19 
•20 
•0007 
•0028 
•006 
•Oil 
•017 
•025 
•034 
•044 
•056 
■069 
•084 
•100 
•20 
•21 
•0007 
•0029 
•007 
•012 
•018 
•026 
•036 
•047 
•059 
•073 
•088 
•105 
•21 
•22 
•0008 
•0031 
•007 
•012 
•019 
•027 
•037 
•049 
•062 
•077 
•092 
•110 
•22 
•23 
•0008 
■0032 
•007 
•013 
•020 
•029 
•039 
■051 
•065 
•080 
•097 
•115 
•23 
•24 
•0008 
•0033 
•007 
•013 
•021 
•030 
•041 
•053 
•067 
•083 
•101 
•120 
•24 
•25 
•0009 
•0035 
•008 
•014 
•022 
•031 
•042 
•056 
070 
•087 
•104 
•125 
•25 
•26 
•0009 
•0036 
•008 
•014 
•022 
•032 
•044 
•058 
•073 
•090 
•109 
•130 
•26 
•27 
•0009 
•0037 
•008 
•015 
■023 
•034 
•046 
•060 
•076 
•094 
•113 
•135 
•27 
•28 
•0010 
•0039 
•009 
•015 
•024 
•035 
•047 
•062 
•079 
•097 
•118 
•140 
•28 
•29 
•0010 
•0040 
•009 
•016 
•025 
•036 
•049 
•064 
•081 
•101 
•122 
•145 
•29 
3 !) 
•0010 
•0042 
•009 
•017 
•026 
•037 
■051 
•067 
•084 
•104 
•126 
•150 
•30 
15 
30 
45 
1.0 
1.15 
1.30 
1.45 
2.0 
2*15 
2-30 
2-45 
30 • 
2 In like manner, when the observations are not simultaneous, the thermome- 
tric chart may be of use, by shewing the change of temperature, fiom one hour 
to another, in the different monhs. 
