again for higher degrees of heal, but not for lower degrees. As Mr.Wedgwood’s thermometer begins at the lowest degree of ignition,and Fahrenheit’s goes no higher than the boiling point of mercury,Mr. Wedgwood continued to fill up the interval of the scale byusing a piece of silver instead of his common thermometer-pieces;and that in this way lie has found that 130 degrees of Fahrenheitare equal to one ot his. He has accordingly, by observing thisproportion, continued Fahrenheit’s scale to the top of his own.We are now therefore enabled to give a scale of heat from thehighest degree of heat produced by an air-furnace to the greatestdegree of cold hitherto known, which was produced at Hudson’sBay in Dec. 1784, by a mixture of vitriolic acid and snow. Ofthe remarkable degrees between these extreme points we shall laybefore our readers
Fuhren- If'edg-A SCALE. Tmt's wood’s
scale, scale.
Extremity of Wedgwood’s scale...32277° 240°
Greatest heat of his smail air-furnace.21877 160
Cast iron melts. 17977 130
Greatest heat of a common smith’s forge.17327 125
Welding heat of iron, greatest.13427 95
--least.12777 90
Fine gold melts. 5237 32
Fine silver melts. 4717 28
Swedish copper melts. 4587 27
Brass melts. 3807 21
Heat by which his enamel colours, are burnt on....,. 1857 6
Bed-heat fully visible in day-light... J077 0
Bed-heat fully visible in the dark. 947 1
Mercury Boils, also linseed and other expressed
oils. 600
Oil of turpentine boils. 560
Sulphuric acid boils. 546
Head melts... 540-
Bismuth melts. 460
Tin melts. 403
Sulphur melts. 244
Nitrous acid boils., iiti 212
Cow-milk boils. 213
Water Boils. 212
Human urine boils. 206
Brandy boils. 190
Alcohol boils. 174
Serum of blood and white of eggs harden. 156
Bees wax melts. 142-
Heat of the air near Senegal sometimes. HI
Hens hatch eggs about. 108
Heat of birds from. 103 to.Ill
Heat of domestic quadrupedsfrom.,. 100 to 103
Heat of the human body. 99 to 99
Heat of a swarm of bees. 97
Heat of the ocean under the equator. 80
Butter melts. 74
judphuric acid of the specific gravity of 1780 freezes at 45
Hit of olives begins to congeal. 43
Heat of hedgehogs and marmots in a torpid state. 39J
Water Freezes and snow melts. 32
Milk freezes. 30
fine and common vinegar freezes... 28
tuman blood freezes.... 25
strong wines treeze. 20
' n >xture of one part of alcohol and three parts of water
. Feezes. 7
g 'fixture of snow and salt freezes. 0 to 4
r sndy, ot a mixture of equal parts of alcohol and water
g Feezes..... — 7
P'rit of wine in Reaumur’s thermometer froze at T01-
x, neo . — 34
CoV^ CURY Freezes . 39 or 40
01c J produced by Mr. Macnah at Hudson’s Bay by a
Sl^ure of vitriolic acid and snow. — 69
file , HRMOPYLjE, in ancient geography, a narrow pass or de-tail’ betw een the Sinus Maliacus, on die L. and the steep moun-3 reaching to Oeta, made dreadful by unpassable woods, onv OWj v — no. 207.
the W. leading from Thessaly to Locris and Bceotia. It is famousfor the brave and unparalleled stand made by Leonidas, king ofSparta, and 300 Spartans, against the whole army of Persia ;and also for the Amphyctiones, the common council or statesgeneral of Greece assembling there twice a year, in spring andautumn.
THERMOSCOPE, and an instrument shewing
the changes happening in the air with respect to heat and cold.The word thermoscope is generally used indifferently with that ofthermometer, though there is some difference in the literal importof the two ; the first signifying an instrument that shews, or exhi-bits, the changes of heat See. to the eye ; and the latter an instru-ment that measures those changes; on which foundation the ther-mometer should be a more accurate thermoscope, &c,
THESEA, in antiquity, feasts celebrated by the Athenians inhonour of Theseus , consisting ofspoits and games, with mirth andbanquets; such as were poor and unable to contribute to themwere entertained at the public expence.
THESEUS, a famous hero of antiquity, ranked among thedemi-gods. He was the son of jEgeus king of Athens . He threwSciron, a cruel robber, down a precipice ; fastened Procrustes ty-rant of Attica to a bending pine, which being let loose tore himasunder; killed the Minotaur kept in the labyrinth by king Minos in Crete ; and by the assistance of- that prince’s daughter, Ariadne ,who gave him a clue, escaped out of that labyrinth, and sailed withhis deliverer to the isle of Naxos , where he had the ingratitude toleave- her. Theseus afterwards overcame the Centaurs, subduedthe Thebans, and defeated the Amazons . He assisted his friendPirithous in his expedition to hell to carry off Proserpine ; butwas imprisoned by Pluto, till be was released by Hercules. Healso established the Isthmean Games, in honour of Neptune ;united the twelve cities of Attica; and founded a republic there,1236 B. C. See tEgeus, Ariadne, Hipfolytus, Minos, Mi-notaur, Ph ;edra, See.
THESIS, [3-I0-I;] a general position which a person advances,and offers to maintain. I11 taking degrees in universities, the can-didates are generally obliged to write a thesis which they must af-terwards defend.
THESIUM, Base Fluellin; in botany, a genus of plantsof the class pentandria, and order monogynia. Calyx one-leaved, into which the stamens are inserted ; nut inferior, one-seeded. There are nineteen species, almost all of which are foundat the Cape of Good Hope .
THESPIS, a famous Greek tragic poet, and the first representerof tragedy at Athens . He carried his troop from village to villagein a waggon, from which they performed their pieces. Alcestis was the first tragedy they performed at Alliens, 536 B. C. SeeTheatre.
THESSALIAN CHAIR, so called from Thessaly, where chairsof this figure were most in use ; it is recommended by Hippocrates in place of a machine for reducing a recent luxation of the shoul-der-bone. The back of this chair is perpendicular to the seat, asGalen tells us; by which construction it is accommodated to theoperation.
THESSALONICA, a citjr of Macedonia , anciently calledTherma, and now Salonichi. See Salonichi.
THESSALY, a country of Greece , whose boundaries havebeen different at different periods. It was bounded on the S. bythe southern parts of Greece , or Grtecia Propria; E. by the iEgean;N. by Macedonia and Mygdonia ; and W. by Illyricimi andEpirus. It was generally divided into four provinces, Thessa-liotis, Pelasgiotis, Istiieotis, and Phthiotis, to which some addMagnesia. It has been severally called rEmonia, Peiasgicum,Argos, Hellas , Argeia, Dryopsis Pelasgia, Pyrrhata, &c. Thename of Thessaly is derived from Tbessalus, who was its first nvo-
" THETFORD, a borough of England, in Norfolk, 30 milesS. S. E. of Lvnn Regis; and 80 N. E. of London . Lon. 0. 50. E.Lat. 52. 28. N.
THETIS, in Pagan mythology, the wife of Oceanus. and themother of Nereus and Doris, who were married to eacli oilier; xand from this marriage sprung the fabled nymphs of the earth andsea.
THEVENOT, Melchisedec, librarian to the king 01 France ,and a celebrated writer of travels., was born at Paris in 1621. Fie9 A travelled