H Y D
Names and Situation of the Stars.
B Longitude
( 271 )
H Y D
Antepenultimate of the Tail £5 Laft but one of Tail beh. Ctrms
In the Extremity of the Tail
60
Informes following Hydra's t Tail, between Libra, Cen- < taurus, and Lupus. 1
6j
20 32 08
22 42 30
1 99 34
4 18 31
5 5-2 38
8 20 00
9 n jt
12 23 42 12 49 10 1? 01 49
14 08 ;S
If f2 OI
16 45 [9
Latitude.
t
»
H 33 '3 43 12 02
18 06
12 00
13 04
37 11
12 f4
14 02
21
26
8 J7°4
9 01 j-6 9 26 yo
II 03 09 10 12 JO 13 2? J2
HYDRAGOGUES, a Species of purgative Medicines 5 being fuch as are fuppos'd peculiarly fitted to difcharge fe- rous, or watery Humours. See Purgatives.
The ftrongeft Catharticks, Dr. ghiincy obferves, chiefly anfwer to the Character of Hydragcgues ; in that by their forcible ihaking and vellicating the Bowels and their Ap- pendages, they fqueeze out Water enough to make the Stools appear little elfe. See Cathartic.
The principal Hydragcgues, on the common Opinion, are the Juices of Elder, of the Root of Iris, of Soldanella, Mechoacan, Jalap, l$c.
In the general, all fudorific, aperitive, and diuretic Medi- cines, ate Hydragcgues.
The Word is form'd of yjlaf, Water, and a.ynv, to draw, to lead.
HYDRARGYRUM, a Name the Chymifts give to Mercury or Quickfilver. See Mercury.
The Word is Greeks form'd of SJbif, aqua, Water, and rtfjup©-, argentum, Silver, q. d. Water of Silver, by reafon of its refembling liquid or melted Silver.
HYDRAULICKS, that Part of Staticks which confiders the Motion of Fluids, and particularly Water 5 with the Application thereof in artificial Water-works. See Wa- ter.
To Hydraulicks belong, not only the conducting and railing of Water, with the conftru&ing of Engines for thole Pur- poles ; but alio the Laws of the Motion of fluid Bodies. See Motion.
Hydroftaticks explain the Equilibrium of Fluids, or the Gravitation of Fluids at reft : Upon removing that Equili- brium, Motion enfues ; and here Hydraulicks commence.
Hydraulicks, therefore, fuppofe Hydroftaticks ; and the generality of Writers, from the immediate Relation between the two, join them together, and call them both either Hy- draulicks or Hydroftaticks. See Hydrostaticks.
The Laws of Hydraulicks the Reader will find under the Article Fluid.
And the Art of railing Waters ; with the feveral Machines employ'd for that Purpole, as Siphons, Tumps, Syringes, Foun- tains, fttsd'Fau, Fire- Engines, &c. are defcrib'd under their proper Articles, Siphon, Pump, Syringe, Foun- tain, FiRE-figrae, &c. ,'•',,. „ ,.. .. „
The Word is deriv'd from the Greek, «%»*> punting Water, form'd of SJbp, aqua, Water, and ttuh'.s, ZW0, Pipe or Flute : The Realbn whereof is this ; that at the Time of the firft Invention of Organs, being unacquainted with the Method of applying Bellows to blow them, they made ufe of a Catarad or Fall of Water to make a Wind, and found them. See Organ. .
The principal Writers who have cultivated and improv d the Hydraulicks, are Jo. Ceva, in his Geometria Moms : Jo. "Bap. Balianus, He Mom Naturali Gravium, Sohdorum Ss liqiiidorum: Mariotte, in his Moummem des Baux & autres Fhiides : Dom. Guglielmini, in his Menfura Aquarian Fluentium, where the higher Laws of Hydraulicks are re- due'd to Praftice : Sir If. Newton, in 'Phil. Nat. 'Prmc. Ma- themat. And Varignan, in the Memoirs of the Royal Aca- demy of Sciences. . .
As to Hydratilick Machines, Hero of Alexandria is the firft who has wrote thereon. Of the Moderns, the Principal are Solomon de Caux, ml French Treatile of Machines, and chiefiv of Hrdraulick ones : Caff. Schottus m his Mechanics Hvdfaulico 'Pneumatics ■: DeChales in his Mitndus Mathe- maticus ; 'Boeder in his Archittttura Curiofa : And Luc. Anthonms Worths.
HYDRAULO-Pneumatical, a compound Term ap- ply'd, by feme Authors, to fuch Engines as raife Water by means of the Spring of the Air. See Air, Water, En-
C Mr.'soi.& mentions a very pretty Fountain, which he calls Hydraulo-'Pneumatical . made by the Spring of the Air ureffingup Water in a Pipe, upon the Airs being ex- haufied out of a Receiver, and thus the Weight of the At- molphere' taken off. SeeFouNTAjN, Vacuum, &e.
f
HYDRELjEON, or Hypreljeum, i» Pharmacy, 3. Mixture of common Oil and Water. See Oil and Wa- ter,
HydreUon taken internally, excites Vomiting ; externally, it is Anodyne, and promotes Suppuration.
The Word is a Compound of the Greek, lUif, aqua, Water, and ihatov, Oleum, Oil.
HYDRENTEROCELE, in Medicine, a Hernia, or Tu- mor occafion'd by a Defcent of the Inteftines, and Water along with them, into the Scrotum. See Hernia.
The Word is compounded of i?J!»f , Water ; irnejv, I"- teftine ; and wfAH, Tumor.
HYDROCAN1STERIUM, a Fire-Engine 5 or a Ma- chine which fpouts Water plentifully and with Force, to be apply'd to the extinguiihing of Fires and Conflagrarions of Houfes, {jfc. See Fire, Spouting, ££jc.
We have various Contrivances to this Effect. — The firft, and which is, as it were, the Balis of the reft, is a Pump inclos'd in a Ciftula or wooden Vehicle fill'd with Water, and mounted on Wheels ; the Pump being wrought with long Levers which come out of the Ciftula ; and the Water it raifes directed to the Place by means of a jointed Tube, See Pump.
The Dutch and othets ufe a long flexible Tube of Lea- ther, Sail Cloth, or the like, which they carry or conducl in the Hand from one Room to another, as Occafion requires $ fo that the Engine may be apply'd where the Fire is only within -fide, and does not burft out to expofe it to its external Aclion.
To improve on rhis original Fire-Engine, they have fince contriv'd to make it yield a continu'd Stream ; by fubftituting a forcing or preffing Pump in lieu of the fucking Pump. See Forcing 'Pump.
HYDROCELE, in Medicine, a Swelling or Bloating of the outer Integument or Skin of the Scrotum, occafion'd by watery Humours caft or detain'd therein.
The Word is furm'd of the Greek, tj'Ap, Water, and p&wuy, I caft.
The Hydrocele is diftinguifh'd from an Hernia or Defcent, in that the firft is form'd by flow Degrees, and the latter all at once. See Her.nia.
Youth is moll expos'd to the Hydrocele. — It is cur'd by drying Medicines ; or by letting out the Water with a Lancer, a Seton, or the like. — But thefe only amount to a palliative Cure : To go to the Bottom of the Dileafe, re- courfe muft be had to Cauteries.
The Word is compounded of the Greek, y'</iae, aqua, and juIab, Tumor.
HYDROCEPHALUS, or Hydrocephale, in Medicine, a watery Head, or Dropiy in the Head. See Head.
The Hydrocephalus is a Congeftion of Water in the Head, fo as to diftend and render it foft. See Dropsy.
There are three Kinds of Hydrocephaly The firft, when the Watet is gather'd between the Skull and the Skin : The fecond, when between the Skull and the Brain: And the third, when the Water is collected in the Ventricles of the Brain.
Children are more liable to Hydrocephali, than Adults $ by realbn their Head is foft, and has been much comprefs'd in the Womb ; or, perhaps, by their having been too rough- ly handled by the Midwife. — Add, that the Bones of Childrens Heads being very foft, and their Sutures not yet exaffly clos'd ; they eafily open, and give Way to an Influx; of Water from without ; whereas in Adults, the Bones of the Cranium are very hard, and clofely bound together. See Cranium.
The Hydrocephalus is a Difeafe very difficult to cure. — There is no Remedy but by levere bliftering on the Sutures. — It fometimes ends in mortal Convullions, and fometimes in Lethargies or Apoplexies.
The Head, in this Cafe, is fometimes extended to a pro- digious Bulk ; fo that the Peribn cannot bear or fuftain it. Of this we have an extraordinary Inftance given us by Dr. Freind, of a Girl two Years old, whofe Head was zS Inches in Circumference. 'Philofoph.TranfaB. N". 318.
The Word is Greek, form'd of 3Ji, f , Water, and rj.pa.hrl, Caput, Head.
HYDROGRAPHICAL Maps, more ufually cill'd Sea. Charts, are Projections of fome Part of the Sea, in Piano ; for the Ufe of Navigation. See Map and Navigation.
In thefe are laid down all the Rhumbs or Points of the Compafs, the Meridians, Parallels, g?c. with the Coafts, Capes, Iflands, Rocks, Shoals, Shallows, ?£c. in their pro- per Places, Proportions, £ffc.
Qorifopher Columbus, the firft great Difcoveter of America, was a Man that earn'd his living by making and felling Hy- drographical Maps. He happen'd to be Heir of the Me- moirs or Journals of a noted Pilot, one Alonfo Sanchez de Hitelva, Captain of a Ship, who, by Chance, had been driven by a Storm to the Ifland of St. Domingo, and dy'd at Columbus's Houfe foon after his Return. This gave Co- lumbus
