REF 
vessel, and 9° when the other side was 
turned. Tliese experiments show clearly, 
that the rays of caloric are reflected from 
polished surfaces, as well sis the rays of 
light. Transparent bodies have the power 
of refracting the rays of caloric, as well as 
those of light; They differ also in their re- 
frangibility. Sq far as experiment goes, the 
most of the rays of caloric are less refrangi- 
ble than the red rays of light. The experi- 
ments of Dr. Herschel show, that the rays 
of caloric, from hot or burning bodies, as 
hot iron, hot water, fires and candles, are 
refrangible, as well as the rays of caloric 
which are emitted by the sun. Whether 
all transparent bodies have the pow'er of 
transmitting these rays, or what is the dif- 
ference in the refractive power of these bo- 
dies is not yet known. 
The light which proceeds from the sun 
seems to be composed of three distinct sub- 
stances. Scheele discovered, that a glass 
mirror held before the fire, reflected the 
rays of light, but not the rays of caloric ; 
but when a metallic mirror was placed in 
the same situation, both heat and light were 
reflected. The mirror of glass became hot 
in a short time, but no change of tempera- 
rure took place On the metallic mirror. This 
experiment shows that the glass mirror ab- 
sorbed the ray s of caloric, and reflected those 
of light ; while the metallic mirror, suffering 
no change of temperature, reflected both. 
And if a plate of glass be held before a 
burning body, the rays of light are not sen- 
sibly interrupted, but the rays of caloric 
are intercepted ; for no sensible heat is ob- 
served on the opposite side of the glass ; but 
when the glass has reached a proper degree 
of temperature, the rays of caloric are 
transmitted with the same facility as those 
of light. And thus the rays of light and ca- 
loric may be separated. But the curious 
experiments of Dr. Herschel have clearly 
proved, that the invisible rays which are 
emitted by the sun, have the greatest heat- 
ing power. In these experiments, the dif- 
ferent coloured rays were thrown on the 
bulb of a very delicate thermometer, and 
their heating power was observed. I'lie 
heating power of the violet, green, and red 
rays, were found to be to each other as the 
following numbers : 
Violet 
16.0 
Green 
Red 
55.0 
The heating power of the most refrangi- 
ble raya was least, and this power increases 
REF 
as the refrangibility diminishes. The red 
ray, therefore, has the greatest heating 
power, and the violet, whicli is the most re- 
frangible, the least. The illuminating 
power, it has been already observed, is 
greatest in the middle of tlie spectrum, and 
it diminishes towards both extremities ; 
but the heating power, which is least at the 
violet end, increases from that to the red 
extremity ; and when the thermometer 
was placed beyond the limit of the red ray, 
it rose still higher than in the red ray, which 
has the greatest heating power in the 
spectrum. The heating power of these in- 
visible rays was greatest at the distance of 
half an inch beyond the red ray, but it was 
sensible at the distance of one inch and a 
half. See Optics. 
REFORMATION, in church history, is 
that amazing change in the religion and 
politics of a great part of Europe whicii 
began to take place in the early part of the 
sixteenth century. An event of such mag- 
nitude, with which the progress of the arts 
and universal learning is so intimately con- 
nected, demands a more enlarged and 
detailed account than the prescribed limits 
of our work will admit. It would, never- 
theless, be highly improper wholly to omit 
the notice of so very important an era in 
the history of Europe. 
At a time when the peace and harmony 
of the Romish Church seemed fully esta- 
blished, and when the authority of the 
Holy See had just received a most signal 
triumph by the labours of die Council of 
the Lateran ; when the address and perse- 
verance of Leo the Tenth had surmounted 
a thousand difficulties, and given peace to 
his dominions ; when Rome had begun 
once more to assume its ancient grandeur, 
and was again become the centre of genius, 
letters, and the arts ; when the dark clouds 
of the middle ages were scattered before 
the rays of science, and the light of genius 
had begun to illumine the moral horizon, 
the attention of the whole Christian world 
was directed to an event that threatened 
nettling less than the speedy ruin of the 
Papal authority, and the complete demo- 
lition of that fabric of religious magnifi- 
cence which the labours, of myriads had 
united to raise, and which the lapse of cen- 
turies had left rather established than im- 
paired. It is curious to reflect, that wha,t 
bid fair to have been the glory and security 
of the church, conspired to her destruction, 
and threatened her total overthrow. Leo 
the Tenth, in aiming to enhance the glory 
