324 ' REPORT—1845. 
Mererorotocy AND Paysics or THE GLoBE.—Those who are desirous of 
studying thoroughly the meteorology and physics of the globe, and carefully 
appreciating all the periodical changes which these two branches of our 
knowledge present, should have recourse to the special report which has been 
published on this subject by a committee of the Royal Society of London*. 
But the observations specified are so numerous and fatiguing, they require the 
operation of so many persons, that it has been hardly possible to find more 
than four or five observatories in Europe in which they are carried out to 
their full extent. In fact it has been undertaken to make observations every 
two hours, night and day; and even, at a certain period in each month, to 
observe the magnetic instruments continuously for twenty-four hours}. For- 
tunately for our plan, such laborious observations are not necessary as far as 
natural history is concerned; our object is to direct attention much more to 
the annual than the diurnal variations, which may in their turn become the 
object of special and simultaneous study. 
The appeal which we now make being addressed especially to naturalists, 
we would restrict our demands to researches which are directly and essen- 
tially connected with the modifications presented by the three kingdoms under 
the influence of the seasons, and avoid fatiguing observers by requiring too 
much from them. 
The thermometer should occupy the first place among instruments to be 
consulted ; and the temperature of the air and earth should be simultaneously 
determined. The thermometer, exposed to the air, at the distance of some 
feet above the soil, should face the north in the shade, so that it may not be 
influenced by reflexion from the adjacent walls. It would be sufficient to note 
its indication each day at a certain hour; 9 o’clock a.m. would be the best. 
It would be necessary, moreover, to ascertain daily its minimum and maxi- 
mum, by means of a thermometer fitted for the purpose. The temperature 
of the earth, especially of those layers in which the roots of trees are imbed- 
ded, deserves special attention. It would be very interesting daily to trace 
the progress of three or four thermometers, the bulbs of which were equi- 
distant in a vertical line: the bulb of the first should be just beneath the 
surface of the soil, and that of the last at a depth of 23 to 30 inches. Pecu- 
liar thermometers, the stems of which project above the surface of the earth, 
and whose bulbs are rather large compared with the size of the tube, are 
constructed for these observations. These instruments should be placed in 
a soil similar to that in which the plants under observation grow, and which 
presents an unbroken surface, sheltered from the direct action of the sun. 
It would, moreover, be interesting to observe, as is done in the garden of the 
Observatory at Brussels, two series of thermometers, one exposed to and the 
other sheltered from the direct heat of the sun. The time for observation, as 
in the thermometer exposed to the air, should be 9 o’clock in the morning. 
The barometer should also be observed at least once a day, and at a fixed 
hour. Care should be taken to note its maxima and minima; and each ba- 
rometric observation should be accompanied by the indication of the thermo- 
meter attached to the instrument. 
The hygrometer also yields valuable indications; but its place may ke ad- 
* Report of the Committee of Physics, including Meteorology, &c., 8vo. London, R. and 
J. E. Taylor, 1840. The instructions for different voyages, published by the Royal Academy — 
of Sciences at Paris, particularly those which M. Arago has inserted in the Annuaire du Bureau 
des Longitudes’ for 1836, may also be consulted with advantage; we can also recommend the 
new meteorological work published by M. Lamont at Munich, and entitled ‘Annalen fiir Me- 
teorologie und Erdmagnetismus.’ 
+ These observations have been continued at the Royal Observatory at Brussels since 1841, _ 
i 
