THERMOMETER. 
a few years, decided to adopt that of Celsius, a 
Swedish philosopher, calling it thermometre centi- 
grade. The Russians still use the graduation of 
De Lisle. The two remarkable temperatures of 
the boiling and the freezing of water are thus 
expressed by the several thermometers men- 
tioned : 
Fahr. Centie. Réaum. De Lisle. 
Boiling point, . 212° 100° 80° 0° 
Freezing point, . 32 0 0 150 
So that the number of degrees of each, included 
between these two points in each, is 180° Fahr., 
100° centig., 80° Réaum., 150° De Lisle; and of 
course 9° Fahr. = 5° centig. = 4° Réaum. = 73° 
De Lisle. Fahrenheit’s is, therefore, the smallest 
degree, and Réaumur’s the largest. The 0° is 
called the zero: all degrees below this are called 
minus, and are prefixed by a dash, thus —20°. In 
the Réaumur and centigrade scales, the degrees 
above zero are also called plus, and marked thus, 
+20°, to prevent one kind being mistaken for 
another. 
Rules for changing the degrees of any one of the 
scales into equivalent degrees of another : 
Fahrenheit into Reaumur.—Each degree of Fahren- 
heit is equal to four-ninths of one of Réaumur. As 
Réaumur, however, reckons his degrees from the 
freezing point, and Fahrenheit 32° below this point, 
we must, when the number of Fahrenheit’s degrees 
to be reduced indicates a temperature above the 
freezing point, first deduct thirty-two, and then mul- 
tiply the remainder by four, and divide the product 
by nine. The quotient is the corresponding number 
of degrees on Réeaumur’s scale. If the temperature 
indicated was less than the freezing point, we must 
also be careful to take the actual number of degrees, 
reckoning from the freezing point. Thus four de- 
grees above Fahrenheit’s zero is twenty eight below 
his freezing point; and this is the number to be re- 
duced to Réaumur’s scale. 
R-aumur into Fahrenheit.—Each degree of Réau- 
mur is equal to 23 of one of Fahrenheit. Multiply 
the given number of degrees of Réaumur by nine, 
and divide the product by four. If the degrees of 
Réaumur were minus, the quotient must be deducted 
from thirty-two, and the remainder will be the 
equivalent degrees of Fahrenheit. Ifthe given de- 
grees were not minus, the quotient must be added to 
thirty-two degrees, and the sum will be the equiva- 
lent sought. 
Fahrenheit into Centigrade. —Each degree of Fah- 
renheit is equal to five ninths of one of the centi- 
grade. Proceed as in the case of Fahrenheit into 
Réaumur, multiplying, however, by five and dividing 
by nine. 
Centigrade into Fahrenhett.—Proceed as in Réau- 
mur into Fahrenheit, multiplying by nine and di- 
viding by five. . 
R-aumur into Centigrade.—Fach degree of Réau- 
mur is equal to 13 of the centigrade. Multiply the 
given number of degrees of Réaumur by five, and 
divide the product by four; the quotient will be the 
equivalent number of degrees on the centigrade scale. 
Centigrade into Reaumur.— Each degree of the 
centigrade is equal to 4 of Réaumur. Multiply the 
given number of degrees of the centigrade by four, 
and divide the product by five; the quotient will be 
the equivalent number of degrees on Réaumur’s scale. 
Extensive tables of the correspondence of these ther- 
mometrical scales, and of some of the most remarkable 
temperatures, may be found in the Treatise on the 
THICK-WIND. 
td 
Thermometer and Pyrometer, in the Library of Use- 
ful Knowledge. 
THERMOPSIS. A genus of ornamental, har- 
dy, yellow-flowered, perennial-rooted herbs, of 
the sophora division of the leguminous order. 
Four species, of from 12 to 25 inches high, bloom- 
ing in June and July, loving a rich soil, and 
propagable by radical division, have been intro- 
duced to Britain from the temperate regions of 
Asia and America. The name thermopsis signi- 
fies “lupine-like,” and is descriptive. 
THESIUM. See Bastarp Toapruax. 
THESPESIA. A small genus of ornamental, 
tropical, evergreen trees, of the mallow tribe. 
The poplar-leaved species, Thespesia populuca, 
called by Linneus Hediscus populneus, is a native 
of India, and was introduced about 80 years ago 
to the botanical collections of Britain. It has 
naturally a height of about 30 or 35 feet ; and it 
loves a soil of peaty loam, and may be propagated 
from cuttings. Its flowers are white ; its timber 
is used by the Hindoos for making wheels, ban- 
dy-bodies, and similar articles; its bark is em- 
ployed in powder as a medicinal alterative, and 
in strong decoction as a wash for certain cu- 
taneous affections; and the juice of the fruit is 
employed in the same way as the decoction of 
the bark.—The great-flowered species, Thespesia 
grandiflora, was introduced to Britain from Porto 
Rico in 1827; and has scarlet flowers, and is 
naturally of similar height to the poplar-leaved 
species.—The name thespesia signifies ‘ divine,’ 
and was suggested by the practice of planting 
the trees around the churches of their native 
regions. 
THICKET. A dense growth of trees or shrubs, 
such as cannot be easily penetrated by men or 
cattle. 
THICK-WIND. A chronically morbid state 
of the lungs of a horse, resulting from certain 
varieties and terminating influences of pneumo- 
nia. It consists in the conversion of part of the 
lungs into a substance similar to the liver, and 
involves a constant abridgment of the proper 
function of the lungs, and occasions continual 
shortness and difficulty of breathing, and is indi- 
cated by comparative shortness and violence of 
both inspiration and expiration, and by the 
emission of a peculiar sound which, when once 
heard, is ever afterwards easily recognised. An 
experienced veterinary surgeon, by means of 
auscultation, can estimate pretty closely the de- 
gree of it, and tell in how far it will diminish 
the horse’s working power, or permanently di- 
minish his value; but he cannot do any thing of 
a surgical or of an actively medicinal nature 
either to cure or to palliate it. The best treat- 
ment for preventing disastrous consequences from 
the disease, and at the same time for gradually 
and most effectually lessening it, is to feed the 
animal on such nutritious food that a compara- 
tively small bulk of it will satisfy him,—to allow 
him ample rest after every meal, before beginning 
