348 Analysis of Scientific Books. 
The periods of the barometric observation are recommended also for 
those of the hygrometer; the mean pressure of the aqueous atmo- 
sphere, however, being calculated from the dew-point at three P. M., 
and the lowest temperature at night of the sheltered thermometer. 
This Essay comprises also some interesting information on the 
change in the freezing point which occurs in time in the best ther- _ 
mometers, and has been imagined to be owing to the alteration of form 
and capacity which the glass undergoes from the pressure of the 
atmosphere upon the vacuum of the tube; as well as some remarks 
upon the correction to be applied to barometers for the expansion of 
mercury and mean dilatation of glass. For information on these points 
the reader is referred to the Essay itself. 
Independently of the Essays to which we have already adverted, 
there are several others of very considerable interest to the philoso- 
pher contained in the volume before us; of these our limits will only 
admit of an enumeration of the titles; they will be found, however, 
not less scientific and important than those on which we have dwelt at 
some length. They are,—1. An Essay upon the radiation of heat 
in the atmosphere. 2. An Essay upon the horary oscillations of 
the barometer. 3. Meteorological observations at Madeira, Sierra 
Leone, Jamaica, and other stations between the Tropics, by Captain 
EF. Sabine, R.A. F.R.S. 4. Meteorological observations in Brazil, 
and in the Equator, by Alexander Caldcleugh, Esq. And 5. Mete- 
orological observations upon heights. The work is also concluded by 
an excellent meteorological journal for three years, commencing on 
the first of September, 1819. 
After the analysis and extracts which we have given in the preced- 
ing pages, it is almost unnecessary for us to remark on the mode in 
which the work is executed. The various subjects, it will have been 
observed, are treated of in a manner highly creditable to the talents 
and scientific acquirements of the author ; whilst the language is in 
gencral elegant and perspicuous ; the reasoning forcible ; and the pro-= 
positions, drawn from principles premised, are logical. To the lover 
of meteorological science in particular, as well as of natural philosophy 
in general, these Essays will be found to form a rich mine of new 
and important information, 
