TEMPERATURE AND METEOROLOGY. 
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shall we say of a third — Magnetism ? Can we doubt its identity when we are 
certified of the earth's magnetic power? And here another suggestion presents 
itself. — Is not cold a substantive essence — a positive entity — and not the mere absence 
of heat ? Why may it not be referred to magnetism, since the magnetic poles are, 
beyond doubt, referable to the coldest and most frozen regions of the globe ? Again, 
as a fourth, we recognise the chemical principle to which so much importance is now 
attached that the term actinism has been applied to it, while its effects and the 
study of it have been distinctively called actino -chemistry. 
This curious principle is described in Mr. Eobert Hunt's " Treatise on the 
Physical Powers of the Universe," as "one of the greatest powers of creation." 
Nearly all, if not all, the phenomena of change, which have been referred to light, 
are now proved to be actinic powers ; and beyond the influence which is exerted by 
it upon all inorganic bodies, that of the solar beams on vegetation is proved by 
common experience. Other principles — called, by Sir John Herschel, Parathermic 
rays — are here alluded to : " they act partly as light, and partly as heat, yet with 
distinguishing difference." 
It is always wise to recur to authorities where any difficult subject requires 
discussion : the progress of science is slow, men oppose each other through a spirit 
of pure opposition, which not merely obstructs, but actually falsifies their own minds. 
Heretofore, since the discoveries of Dr. Black, the doctrine of latent heat has been 
pertinaciously maintained. Now, however, we begin to admit that heat, light, 
electricity, magnetism, and chemical power, are just so many substantive emanations 
from the sun. He then, the Fountain of Light, radiates, or transmits these 
vitalising elements to the earth, which thus becomes the great elaborating medium, 
wherein all the operations that terminate in meteorological phenomena are per- 
formed. Subject to these considerations, what are the principles which should be 
adopted in the construction of our forcing-houses ? If, as has been said, solar 
power produces equability of heat, should it not be the aim of the forcing gardener 
to adopt a method by which any erection that occasionally or generally requires 
artificial excitement, can be heated throughout its entire area with all attainable 
regularity ? 
Yet, whether we consider the old fire-flue, the complicated steam apparatus, the 
hot-wfter pipes, channels, and tanks, the same results present themselves; for 
irregularity of temperature, even to the amount of many degrees, is discovered in 
all of them. 
In a twenty-four feet house, attempted to be warmed as a vinery by a double 
course of hot-water channels, made of twelve-inch square paving-tiles cemented, that 
passed on every side of the erection, the air could never be regularly heated ; its 
temperature varied fully five degrees, and even then the utmost power of a furnace 
which consumed two bushels of coke in twenty-four hours, could not insure 65° 
at the entrance of the " flow " water, during a severe frost, thus rendering it 
difficult to obtain more than 59° at the distance of twelve feet from that entrance. 
VOL. XIV. NO. CLXII. S 
