202 
On the Firs of the Casiya Range , and the 
31 inches, 
100° will require a length of 96°,7 
30 
100, 
29 
103,5 
28 
. 107,1 
27 
111,1 
26 
115,4 
In the same manner, if the barometric scale be supposed to be adapted to the 
standard temperature 60°, then above and below that degree, the length of the whole 
scale (as it is not a scale of equal division, it is better to use this expression) must 
vary in the following proportions. 
At 30° — the length will be ,9376 
40 ,9584 
50 ,9792 
60 1 ,0000 
70 1,0208 
80 1,0416 
90 1,0624 
100 1,0832 
110 1,1040 
120 1,1248 
After this explanation, it is easy to discover the cause of discrepancy in the two 
instruments mentioned before : — the first appears to have been experimentally divid- 
ed at a temperature of 50°, and the other at a temperature below the freezing point, 
or in the depth of winter 
The most convenient method of obviating these sources of error, is to describe 
the lines which mark the divisions of inches and degrees, as parts of rays convey- 
ing to a distant point, instead of drawing them parallel to one another in the ordi- 
nary manner : perpendicular lines may then be drawn parallel to the line of stand- 
ard divisions, at such distances on either side as to intersect new scales of divisions 
adapted to given variations of the bulk of air from pressure or temperature as above 
described. 
Such scales might be printed and attached to common sliding rules, and it would 
be only necessary to have on the Sympiesotneter a single scale of temperature, and 
indeed any air thermometer might then at once be converted to the purpose of a 
barometer on the same principle, 
Q 
V. —On the Firs of the Casiya Range, and the possibility of trans- 
porting them into the Brahmaputra. 
We have much pleasure in publishing the following account of the firs in 
the Cdsiya Range, drawn up by Captain Jones of the Quarter Master General’s 
Department. 
I shall commence by stating that there are only two places, where in my opinion 
the fir timbers could possibly be floated. These are the Suripani four miles N. 
W. of Nancldo, and the Bar-pani, 37 miles east of the former, on the Jaintia road. 
The Sdripiini is just 2000 feet below Nancldo, and 2400 feet above the level 
of the Brahmapfitra, as measured with a barometer, and the same result nearly was 
obtained by using a theodolite : the point measured from, was the bridge of fir timbers 
and planks 60 yards long. The trees here are larger than those above or below this 
altitude. Many may be procured of 2 feet in diameter (bark included) ; the general 
breadth is between 14 and 18 inches in diameter, in the rough state, tapering very 
slightly to the top : the lengths vary a good deal, from 30 to 90 feet in timbers 
of the same thickness. The species appears to be that resembling the Scotch fir, 
haying a long grain and containing a considerable quantity of turpentine, the knots 
being 2 or 3 or more feet distant from one another : the colour of some of the planks 
when dry is yellow, and in these I think there are fewer knots, and further apart, 
whilst in other timbers the wood is nearly white and much softer. 
A little lower down the Sdripdni, after several considerable falls, the fir trees 
are very numerous, and any number from 10 to 13 inches may be found, the wood of 
the same description. These firs do not thrive well after leaving the immense stra- 
tum of sparkling granite which extends to 40 miles, (known) east of Nancldo, 
