Academia scientiarum, or, The academy of sciences being a short and easie introduction to the knowledge of the liberal arts and sciences, with the names of those famous authors that have written on every particular science : in English and Latine / by D. Abercromby ...

Sect. XX. The Mechanicks.

THis Science considereth the quan∣tity of Moving forces, and of Duration of the time in which the Mo∣tion is performed.

The gravity of a Body, is a certain capacity of falling downwards; the cen∣ter of gravity, is that place or point from which if we conceive the Body to be suspended, whatever situation you may give it, it shall retain the same.

The Center of Magnitude, and of gra∣vity, are not always the same, as 'tis evi∣dent in a Bowl half Lead, half Wood.

The Pendula diameter of gravity, or the handle, is a streight line drawn through the center of gravity perpendicu∣larly to the Horizon.

No weight can rest, unless the pen∣dula diameter of gravity, or handle, pass through the place upon which it

leans, or from which the weight is sus∣pended.

In all Planes, the center of the figure, is likewise the center of gravity.

This Art teacheth in general, how to find out the ponderousness of every thing, and how to move things with little strength.

We must not forget in this place a sort of Mecbanism, the knowledge where∣of is of great concern for the good of Mankind; I mean that of Trusses, and Instruments fit for restoring by degrees, any part of the Body to its natural place and situation.

The burst Peritonaeum sometimes gives way to the Intestines, at other times to the Caul. and not seldom, to both, to get out of their natural place, into the Groins, or the Scrotum, there causing a Rupture, called Enterocele, or Her∣nia intestinalis; if the Bowels come out, an Epiplocele, or Hernia omen∣talis; if the Omentum or Caul be out. The Peritonaeum is made up of two

strong, but soft Membranes, which do so contain whatsoever is included in the Belly, that, when sound, nothing can fall out. In Women, the Os pubis is its utmost limit. In Men, its outermost Membrane reacheth further, and consti∣tutes the first proper coat of the Testi∣cles. In the Groin, it comprehends the seminal Vessels, as in a Sheath, called Processus, which being stretched or in∣larged, or coming to burst, is the im∣mediate cause of the lately mentioned Ruptures. We must not nevertheless imagine, that the Peritonaeum cannot be distended, and burst in other places, and therein to cause a Rupture.

The causes which make the Perito∣naeum to Burst or Dilate, are falling, leaping, beating, bearing of heavy bur∣thens, strong Vomitings or Coughing, Obstipation of the Belly, Winds pent in, and vehement motions of the Body.

But I can do no greater service to the Publick, than to inform the World of two of the best Artists I know of in this

kind, both living together in Black Fryers, in London, I mean the Famed Robert Smith, a Scotch Gentleman, and his Son-in-Law, Thomas Jewel, who give daily succesful proofs of their Skill in this kind of Mechanism, their Trusses of what kind soever being so light, so easie, and so fitted to all the motions of the Body, that they are not at all trou∣blesome.

They likewise cure effectually any De∣formity in humane Bodies, occasioned by the preternatural bending outwards, in∣wards, or downwards, of any part thereof, and by such ingenuously contrived En∣gines, as force Nature gently into its first place and situation.

Authors.

Aristotle, Henry Monenthole, Jo∣seph Blancan, Guid Ubald, Stevin, Hero, Robert Vulturius, Cedren, John Baptista Porta, Joseph Boillot, Ranelli, Barbette, Brown, &c.