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of Metallic ones ; adding, that there is nothing more re- quir'd to the Perfection of this Telefcope, but that the Art of polilhing Glaiis be brought to greater Perfection ; for that fbme Inequalities which don't hurt Lens's, are found to affeft Specula, and prevent Objects being feen diftinctly.

The fame Author obferves, thai if the Length of the In- Jtrumem be 6 Feet, and confequently the Semi-diameter of the Concave Speculum 12, the Aperture of the Speculum is to be 6 Inches ; by which Means the Object, will be incrcas'd in the Ratio of 1 to 200 or 300.

If it be longer, or fhorter, the Aperture muff be as the Cube of the Quadraro quadrate Root of the Length, and its magnifying i'ower as its Aperture. The Speculum he orders to be an Inch or two broader than the Aperture.

Aerial Telescope, a kind of Agronomical Telefcope, the Lens's whereof are us'd without a Tube.

In Strictnels, however, the Aerial Telefcope, is rather a particular Manner of mounting and managing long Telef copes, for Cceleftial Obfervations in the Night Time, where- by the Trouble of long unweildy Tubes is fav'd, than a particular Kind of Telefcope. The Contrivance we owe to the noble Hvygens.

CmfruBion of the Aerial Telescope.

1° A tall Pole otMaft, AB (Fig. 46.) the Length the Tube mould be of, is fix'd perpendicularly in the Ground. Before the erecting it, one Side is planed fmooth, and upon it two Rulers fix'd parallel to each other, an Inch and Half apart, including a kind of Groove or Channel between them, reaching from top almoft to bottom. At the Top of the Pole is fitted a little Truckle A, moveable on its Axis, and over it is drawn a Cord G g, double the Length of the Pole, and the Thicknefs of the little Finger, returning into itfelf, and furnifh'd with a piece of Lead, H, equal in Weight to the Lens and a moveable Arm to be fuftained thereby.

Then, a wooden Lath, CD, two Foot long, is framed £b as that it may Aide freely in the Channel ; and in the Middle thereof, is affix' d a wooden Arm E, {landing out a Foot from the Pole, and on its Extremity bearing another, F f, a Foot and Half long, fix'd to it at Right Angles ; both of them parallel to the Horizon.

2° An Object-glafs is included in a hollow Cylinder I K, three Inches long : To this Cylinder is fix'd a Staff, KL, near an Inch thick, and a Foot long, which refls on a brafs Ball M, rhat moves freely in its Cup or Socket underneath : Only, on Occafion, the Ball and Socket are fix'd by a Screw. That the Lens thus equally balanced, may be moved with a fmall Force, a Weight N I of about a Pound, is fufpended, by a firong Wiar NF, by bending which, the common Centre of Gravity of the Weight, the Lens is eafily made to coincide with that of the Bail. To the Staff KL, is fix'd a brafs Style L, which is bent downwards, till its Point be as much below the Centre of the Staff, as the Centre of the Ball is. To the Point is tied a fine filken Thread L V, Which, of Confequence, will be parallel to the StafFK L.

3 An Eye-glafs O, is included in a fhort Cylinder ; and the Staff P V, fix'd to the fame. To this is hung a little Weight S, fufficient to make a Balance. In Q_ ' s ^ x 'd a Handle, R, which carries a tranfverfe Axis, to be held in the Obferver's Hand, and the Staff P V directed towards the Objefl-glafs, is tied to the Thread L V. The Thread pafs'd through a Hole, V, is wound about a little, Peg T, fix'd in the middle of the Staff ; by the turning whereof, the Length of the Thread is fhorten'd or prolong'd at Pleafure.

4° That the Obferver may be able to hold the Eye- glafs ffeady 5 he has a Fulcrum or Prop under his Arm, the Structure whereof appears from Infpedtion of the Figure. Laftly, to keep off the feeble Light flowing from the Air upon the Eye, it is conveniently cover'd with a Circle, Y, perfo- rated in the Middle, fitted on to a moveable and flexible Arm.

TelescopicalAWs, are fuch as arc not vifible to the naked Eye ; but difcoverable only by the Help of a Telefcope. See Star.

All Stars lets than the 6th Magnitude, are Telescopic to a moderate Eye.

TELLER, an Officer in the Exchequer, of which there are Four. See Exchequer.

Their Bulinefs is to receive all Monies due to the Crown, and thereupon to throw down a Bill through a Pipe, into the Tally-Court, where it is received by the Auditor's Clerks, who attend there to write the Words of the faid Bill upon a Tally ; and then deliver it to be enter'd by the Clerk of the Pells, or his Clerk. See Tally and Pell.

The Tally is then fplit or cloven by the two Deputy Cham- berlains, who have their Seals, and whilft the Senior Deputy reads the one Part, the Junior examins the other Part, with the other two Clerks.

Their Places are in the King's Gift, and rhey have, befides their chief Clerk or Deputy, four other Clerks, for the Dif- patclior Bufinefs.

TELLUS, Terra, J, in Aftronomy. See Earth.

(Phyfical TEMPER in a^Mufical

/ Mechanical

\ (Temperament?

£senfe.See< T * MP ** AMENT ) in Mufic.

) (.Tempering.

Temperament, temperamentum, tem- perature, in Phyficks, that Habitude or Difpofition of a Body arifing from the Proportion of the feveral prime or elementary Qualities it is eompofed of. See Quality ancl Element.

The Notion of 'Temperament \ arifes from that of Mixture; where different Elements, as Earth, Water, Air and Fire (or, tofpeakmorejuitly, in the Peripatetic Way, hot, cold, moift and dry_) are blended together ; by their Opposition, they tend mutually to weaken and incroach on each other ; and from the whole, arifes a fort of temperate Crafis, or Coalition of them all, in this, or that Proportion ; whence, according to the Quality that prevails or predominates, we fay a hot or cold, a moifi or dry Temperament.

It is controverted amchg the School-men, Whether thfe Temperament properly comprehends all the Four primary Qualities ? or, Whether thole do not all ceafe, and a new one, a Fifth, fimple Quality, refult from the total Alteration made in the other Four, by their mutual Action on each other ?

Authors diftinguifh two Kinds of Temperaments, viz; Uniform and T)ifform : The Firft, wherein all the Qualities are mix'd in an equal Degree : The Second, where in an un- equal one.

The Uniform Temperament* can only be one; the DifForm admits of Eight different Combinations, fince either any one* or any two of the Qualities may prevail ; whence hot and moijl, cold and moift, HS>c. Further, fbme confidering that the Qualities which do prevail, may not be in equal Degree; and the like of thofe which do not prevail ; make feveral other Combinations or Temperaments-^ and add 12 more to the Number. In effect, as there are infinite Degrees between the higheft and loweft Pitch of any one of the Elements, the different Temperatures may be faid to be Infinite.

Temperament, in Medicine, is particularly understood of the natural Habitude and Constitution of the Body of Man; or the Difpofition of the Animal Humours. See Con- stitution and Humour.

The Notion of this Temperament arifes hence, that the Blood flowing in the Veins and Arteries, is not conceived to be a fimple Fluid \ but a fort of imperfect Mixt, or an Aflemblage of feveral other Fluids. For it does not only confift of the Four fimple, or primary Qualities ; but of Four other fecondary Ingredients compounded thereof, into which it is fuppofed to be refolvable, viz. Choler* 'Phlegm, Melancholly and Blood* properly fo called; See Blood, Choler, Bile, Phlegm, i$c.

Hence, as this, or that Ingredient Humour prevails in a Perfon, he is faid to be of a Choleric, Phlegmatic, Melan- cholic, Sanguine,^. Temperament. See Sanguine, Me- lancholly, Choleric, £Sc.

The ancient Phyficians brought thefe Animal Tempera- ments to correfpond with the univerfal Temper&ments above defcribed : Thus the Sanguine Temperament was fuppofed trf coincide with hot and moifi ; the Phlegmatic with cold and moift, the Melancholic with dry and cold, ££c.

Galen introduced the Doctrine of Temperaments into Phyfic, from the Peripatetic School ; and made it, as it were, the Bafis of all Medicine. The whole of curing Difeafes, confifted in tempering the Degrees of the Qualities, Hu- mours, &c. See Galenical, Decree, £&.

On the Footing Medicine now {lands, the Temperaments are much lefs coniider'd. Dr. §>uincy and other Mechanical Writers, pare away the greateft Part of the Galenic Notion, as uftlefs and uncertain ; and confider the Temperaments ass no other but thofe Diverfities in the Blood of different Perfons, whereby it becomes more apt to fall into certain Combinations in one Body than another, whether into Choler, Phlegm, &c. whence, according to them, People are denominated Choleric, Phlegmatic, i$c.

The Ancients diftinguifh'd two Kinds of Temperaments. in the fame Body j the one ad T'ondus, in Weight ; the other, ad Jitftitiam.

The Temperamentiim ad Tondus* is, where the elementary Qualities are found in equal Quantities, and in equal Propor- tions ; fuch is fuppofed to be in the Skin of the Fingers ; without which they would want Power of diftingui filing Objects, with fufficient Accuracy.

The Temperamentum ad Juftitiam, is that which contains unequal Portions of thofe Qualities, but yet in fuch Pro- portion as is neceflary for the Difcharge of the Functions proper to the Part : Such is the Temperament in a Bone, which contains more earthy than aqueous Parts, to make it more hard and folid, for its Office of fuftain-

Galen