THE PLANTS OF THE GRAMPIANS. 55 
proved form ofa narrow mahogany box, adapted for suspen- 
sion across the chest or back, by means ofa strap passing 
overone shoulder, and under the opposite arm; the bulb of 
the thermometer, and the bulb containing the gas, being both 
together at the top of the instrument—an important improve- 
ment, since miscaleulations are thus avoided, which might 
otherwise occur through inequality in the temperature of 
the two bulbs and tubes. The Sympiesometer is an inge- 
nious modification of the barometer, more portable in its 
dimensions, and the use of which is readily learned by the 
printed instructions given with it to the purchaser ; but some 
practice is necessary before much reliance can be placed 
upon its indications, as various causes may affect the results 
in the hands of a novice. Some of these I will here notice 
for the benefit of others, having myself formerly felt the want 
of such suggestions. 
There is one considerable objection to the Sympiesometer, 
which will not apply to the barometer, namely, not admit- 
ting of a reversed position in travelling, without great risk of 
being rendered utterly useless. On this account, it cannot 
be carried in a portmanteau, nor be safely left in any situation 
where it is likely to be meddled with by persons unacquainted 
with its construction and use. And, like most philosophical 
instruments formed of glass tubes, its fragility makes. it very 
ill adapted for the risks of public conveyances, and of the 
shakes and knocks almost unavoidable in botanical rambles 
and scrambles on the mountains. Altogether, this instru- 
ment, like many other useful commodities, is often sadly in 
the way, and felt to be nearly as inconvenient in the light of 
a travelling companion, as we might suppose an infant likely 
to prove when without its nurse. Literally,. while journey- 
ing from place to place, and whilst ascending and descending 
hills, I carried the Sympiesometer in baby-fashion, except 
thata strap gave the ordinary support, and the hands were 
called into use only occasionally, to avoid extra risks of blows 
and jars. 
But let us suppose the risks of travel are passed, and the 
