REPORT ON METEOROLOGY. 
245 
cially, produce such grand and varied spectacles, and indicate 
in the most beautiful manner the constancy of the laws by which 
the temperature and variable conducting powers of the materials 
on the surface of our globe, modify the distribution of atmo¬ 
spheric vapours*. The subject is one of wide extent, and may 
at a future period disclose very interesting results ; it does not 
appear, however, to present such definite points of investigation 
as to be reckoned among the first objects of the scientific me¬ 
teorologists in search of general laws. 
The nomenclature of the clouds, adopted by Mr. Howard, 
is a happy specimen of a conventional system, and is well cal¬ 
culated to stamp with a definite character the future results 
of observation ; each species of cloud very probably is attended 
with a characteristic hygrometric condition, and most likely 
exists between fixed limits of altitude. I do not recollect to 
whom we are indebted for a suggestion which well deserves at¬ 
tention, but which cannot be accomplished without that essential 
condition which it seems the fate of Meteorology to want,—Co¬ 
operation. If by a series of little maps of the state of the sky 
we could represent the daily condition of the atmosphere over 
a large continent such as Europe, what curious results might 
not be unfolded! The determination of the existence of im¬ 
mense clouds covering whole countries for days together, while 
others were under sunshine—the watching of the progress of 
these clouds, not so much by the influence of wind, as by a 
gradual process of hygrometric dissolution and recomposition, 
day after day, would give us more insight into the operations of 
the higher atmosphere on the large scale, than a thousand in¬ 
sulated observations. 
The diurnal extremes of the hygrometric state are of course 
limited by those of the temperature of the atmosphere ; the 
minimum temperature causing a deposition of moisture when it 
exceeds a certain amount, and the limit within which the maxi¬ 
mum temperature of the air is kept, (86° Fahr. being the maxi¬ 
mum over the ocean at any point of the globe f,) preventing the 
existence of vapour beyond a certain degree of tension. Dr. 
Anderson has in an elegant paper shown the connexion which 
is hence established between the dew-point at any time of the 
day, and the minimum temperature of the same period J. 
We cannot propose to meteorologists a finer problem for 
complete solution, than that of the moist bulb hygrometer; 
which will require a close analysis of all that has hitherto been 
* See Sir Humphry Davy “ On the Formation of Mists,’ Phil. Trans . 
f Arago, Annuaire , 1825, p. 186. 
J Edinh. Phil. Journal , vol. xi. 
