170 
No. 1 showed 88, No. 2 at various times indicated *92 88 95 
Do. 78 80 84 
Do. 73 79 79 81 
Do. 42 48 49 48 
Besides these I had the loan for a short time of two other 
superior instruments, made by known makers, and in each 
case I found great irregularity of action. These four instru- 
ments cost from 35 — 45 francs each. A short pillar gut 
hygrometer was also lent me, but as these should never be. 
considered as meteorological instruments (though they may 
be useful in a room), comparison of their action is here un- 
necessary. 
In consequence of these comparisons I do not feel inclined 
to place absolute reliance upon the hair hygrometer, though I 
think it most useful to have one in every meteorological 
box, as it may help over some points of difficulty ; for 
instance, you go to take your reading and find that the ice 
on the wet bulb has only partially thawed, and consequently 
you know that the reading is valueless, but by now noticing 
the hair hygrometer and returning in half an hour to com- 
plete the observation, fairly reliable results may be obtained. 
RegnauWs Hygrometer. 
Towards the end of the winter I obtained from England 
a Regnault’s hygrometer, but as the quicksilver of one of 
the thermometers became divided on the journey, through 
there being some air in the tube, I have not made as many 
control observations as I otherwise should have done, but 
the observations made will nevertheless enable me to form 
an idea as to which formula should be used, and further, as 
this is an instrument requiring considerable practice, I am 
glad to have had some experience with it, as I see that here 
much will depend on its being properly placed, because, as 
* The last examples are given uncorrected, whereas I applied a cor- 
rection to the series previously quoted, commencing Jan. 7th. Of course 
it will be understood that the correction must be the addition or sub- 
traction of equal arcs and not of degrees of moisture* 
