286 
On the mean Temperature of Calcutta. 
[Sept. 
light yellow, not unlike that of a leaf in England at the fall of the year. I am in- 
formed that, when alive, or but recently dead, the hue of the insect is of the liveliest 
green, which may be preserved unimpaired for any length of time, by simply 
covering it with cotton wool, excluding the light and air 5 . It appears extraordi- 
nary that the Mantis strum aria, or Leaf Insect of America, which, in specific 
characters, would seem to agree with our insect, is yet totally different in the 
peculiarity of external form from which both derive their names. The Mantis or 
P hy Ilium sicdfolium is described as being a native of the Molluccas, and although 
it is well known, and specimens are not uncommon, I am not aware that it has 
been found before in continental India 6 . Should this be the case it will form one 
proof more of the similarity, in point of natural productions, both animal and 
vegetable, of our territories on the eastern frontier, to the interesting islands of the 
archipelago. 
VI . — On the Mean Temperature of Calcutta; with a table for reducing 
to the Maximum or Minimum., observations of the Barometer, made at 
any other time of the atmospheric tide . 
Sir, 
To the Editor of Gleanings in Science. 
t 
l send you a chart of the 'temperature of Calcutta for each month of 1829. 
It is formed, by protracting the temperature at the different hours, as given in the 
Meteorological Register, (correcting a few typographical errors,) and then draw- 
ing through the points, so as to get as nearly as possible the temperature of the 
whole twenty-four hours. Knowing how little room you can afford, I have endea- 
voured to condense it as much as possible, so as to he consistent with distinctness, 
and the size of your page, and shall do the same in my remarks. The mean of 
1€ o’clock a. M. and p. M. gives 78°, 0 while 4 A. M. and p“ M. gives 78°, 2, the mean 
of both being 78°, 1, which is probably very near the true temperature of the whole 
year. 
The mean of each month may be seen in the annexed table. 
January, I 66°,2jl April, I 85°, 41 July, I 81°, 8 October, 79°, 2 
February, 69 ,8 May, / 85 ,7 August, 82 ,0 November, 74 ,2 
March, J 80 ,0j( June, / S3 ,7 / / September, j 82 ,8 December , 66 ,6 
Comparing the mean temperature of the whole year with that of each month, 
we find a correction to be applied to each, in order to have the mean of the year. 
Thus the mean temperature of the year, is equal to that of : — 
Jan+ll°,9 ] Feb. -f8°,3 1 March— 1°, 9 1 April— 7°,3 I May— 7°, 6 1 Jud— 5 °,6 
July— 3 ,7 | Aug. _3 ,9 | Sept. —4 ,7 | Oct 1,1 j Nov.+3 ,9 | Dec. + 11 ,5 
These numbers may probably vary in different years, yet they give some in- 
formation which would be increased by farther comparisons : — 
Since August is as much above the mean as November is below it, these two 
months will probably give the mean of the whole year. 
By looking at the Chart it will appear that the greatest range of temperature 
occurs in December and January, when it amounts to about 18°.— The least range 
is in July, amounting to about 6°. 
If there lmd been room, without confusing the Chart, I should have added the 
range of the wet bulb thermometer. 
1 send you also a table for reducing to the Maximum or Minimum, Barometric 
observations made at any time of the atmospheric tide. It is calculated on the 
pnncipJe, that the amount of reduction is as the square of the time from the nearest 
maximum or minimum. It will be found, by protracting the variations on a large 
scale, that they observe a law not sensibly different from this. 
/.e same thing: might be deduced from a more general consideration of the 
subject. 
on ® sent ^ Manipur preserved in this way. It retained i s color, a 
nght greeu, perfectly.— G. S. 
I also Ip!! 1 / 8604 fr ° m S y lh . et many years ago, by the late Mr. Smith, to Dr. Roxburgh. 
Isle ofFr' ‘ lVer ^ e s P ec i ,neu hereto Dr. Brewster, last year. It is also found at the 
— (j.o. 
