palsy, &c[2].
But a much more satisfactory and useful distinction is made by Sylvius
de la Boe into those tremors which are produced by attempts at
voluntary motion, and those which occur whilst the body is at rest[3].
Sauvages distinguishes the latter of these species (_Tremor Coactus_)
by observing, that the tremulous parts leap, and as it were vibrate,
even when supported: whilst every other tremor, he observes, ceases,
when the voluntary exertion for moving the limb stops, or the part is
supported, but returns when we will the limb to move; whence, he says,
tremor is distinguished from every other kind of spasm[4].

[Footnote 2: Junckeri conspect. de tremore.]

[Footnote 3: Sect. V. Ubi autem solito pauciores deferunter
ad eadem organa spiritus animales, imperfectae ac imbecillae
observantur fieri eadem functiones, in motu tremulo et
infirmo, nec diu durante, in visu debili, ac mox defatigato,
&c.

Sect. XIX. Inaequaliter, inordinate, ac praeter contraque
voluntatem moventur spiritus animales per nervos ad partes
mobiles, in motu convulsivo, ac tremore, quassuve membrorum
coacto.

Distinguendus namque his tremor quiescente licet ac
decumbente corpore molustus a motu tremulo, de quo dictum.
Sect. V. Quique quiescente corpore cessat, eodemque iterum
moto repetit.

Sect. XXV. Coactus tremor debetur animalibus spiritibus
inordinate ac continuo, cum aliquo impetu ad trementium
membrorum musculos per nervos propulsis: sive fuerit is
universalis, sive particularis, sive corpus fuerit ad huc
robustum sive debile, Sylvii de la Boe. Prax. lib. i. cap.
xlii.]

[Footnote 4: Nosolog. Methodic. Auctore Fr. Boissier de
Sauvages, Tomi. II. Partis ii. p. 54. 1763.]

A small degree of attention will be sufficient to perceive, that
Sauvages, by this just distinction, actually separates this kind of
tremulous motion, and which is the kind peculiar to this disease, from
the Genus Tremor. In doing this he is fully warranted by the
observations of Galen on the same subject, as noticed by Van
Swieten[5]. "Binas has tremoris species[6] Galenus subtiliter
distinxit, atque etiam diversis nominibus insignivit, tremor enim
([Greek: trom &]) facultatis corpus moventis et vehentis infirmitate
oboritur. Quippe nemo, qui artus movere non instituerit tremet.
Palpitantes autem partes, etiam in quiete fuerint, etiamsi nullum
illis motum induxeris palpit