HEAT AND ITS APPLICATION. 35 
first-rate quality, and the adaptation by cement perfectly correct : this is a circum- 
stance of great moment, as a predominance of moisture, though at command, is 
readily avoided. 
To persons with whom economy of fuel is a first consideration, some modifica- 
tion of the furnace becomes essential ; for, although by filling the cylinder with 
coke, curtailing the draught at the ash-pit opening, and nearly closing the chimney- 
damper, the high temperature then existing can be sufficiently supported by 
radiating surfaces so extensive during the longest winter nights; yet great 
assiduity is required, throughout the day, to raise a full temperature by the rapid 
combustion of the coke. We therefore urge the necessity of a new modification 
of furnace, giving greater capacity upon the principle of the oven, wherein fuel of 
more durable and less costly materials can be constantly burnt, and always kept 
alight, without that unremitting attention which the small cylinder coke-boilers 
require. 
Upon accurately investigating a house, 25 feet by 9, and of proportionate average 
height, we found a temperature of 69° — 70°, with brisk wind at N.N.W., and 3° 
of frost at 9 p. m. The upper surface of the slates measured 86 square feet, and 
the internal contents of the two channels were estimated at very nearly 286 
gallons. The heat of the water, at its entrance into the channel, was 129°, that 
at the termination of the exit-channel, close to the descending return-pipe, 125° ; 
while at 20 feet distance, and not remote from the centre of the course, the index 
marked about 127° ; so regular and equable were the communication and distri- 
bution of heat evolved from about a peck of ignited coke. 
We submit these facts as a standard of calculation ; observing, that if 280 
gallons of water can thus be heated to 130°, a proportionate increase of combustible 
matter would diffuse heat in proportion to a house of much greater dimensions. 
The agency of heat is peculiarly influential, but it requires the presence of pure 
solar light to render it a safe application to growing plants : in that radiance there 
is a combination of principles which, though not clearly comprehensible, manifestly 
includes electro-magnetism, and heat. The latter principle has been usually 
restricted by philosophers to what they term the prismatic red ray, while pure 
magnetism, the principle of cold, is referred to the blue and violet rays, seen at 
the opposite side of the spectrum. 
Electricity^ — the great agent of all attractions, and that ethereal essence which 
retains the elemental material substances in their natural state of union, — appears 
to demand the presence of all the rays, united in the form of white light : hence, 
the sunbeam becomes the vitaliser of vegetative nature ; hence, the flow of the sap, 
the peculiarities of movement during day and night, the transpiration and imbibi- 
tion through the " stomates " of the foliage, and all the various and variable 
changes of tint in leaves and flowers. 
The great Thomas Andrew Knight pointed out, many years ago, not only the 
uselessness, but the danger, of keeping up strong, moist temperature during the 
