VOL. IX.] PHILOSOPHICAL TRANSACTIONS. IQQ 



Of very exact Portable Watches ; from the Journal des Sgavans. By M, Huy" 



gens. N° 112, p. 272. 



The watches of this invention being made small, will serve for very exact 

 pocket- watches ; and when made larger will be useful every where else, and 

 particularly to find the longitudes both by sea and land, as their movement is 

 regulated by a principle of equality, as that of pendulums is in a cycloid, and 

 that no kind of carriage shall be able to stop them. The secret of the inven- 

 lion consists in a spiral spring, fastened by its innermost end to the axis or arbor 

 of a poised balance, larger and heavier than is usual, which turns on its pivots; 

 and by its other end to a piece that is fastened to the watch-plate; which spring, 

 when the balance-wheel is once set agoing, alternately shuts and opens its 

 spires, and with the small assistance it has from the watch-wheels, keeps up the 

 motion of the balance-wheel ; so that, though it turn more or less, the times 

 of its reciprocations are always equal to one another. 



In fig. 1, pi. 8, the upper plate of the watch is AB ; the circular balance- 

 wheel CD, of which the arbor is EF; the spring turned spirally, GHM, 

 fastened to the arbor of the balance-wheel at M, and to the piece that is fixed to 

 the watch-plate at G ; all the spires or windings of the spring being free, with- 

 out touching any thing ; NOPQ is the cock, in which one of the pivots of the 

 balance-wheel turns; RS is one of the indented wheels of the watch, having a 

 balancing motion, which the balance-wheel of rencontre gives to it. And this 

 wheel RS catches in the pinion T, which holds on the arbor of the balance,- 

 whose motion by this means is preserved as much as is necessary. 



Extract of a Letter dated Amsterdam, Oct. 9, 1674, to the Editor, by Dr. 

 Swammerdam, of an unusual Rupture of the Mesentery. N° 112, p. 273. 



The accompanying figure (fig. 20, pi. 8) represents a fatal volvulus or iliac pas- 

 sion, caused by a rupture of the mesentery, and its tight convolution round the 

 intestines. — A. A. The intestinum ileum distended in a surprising manner by 

 chyle, air, and faeces, and in an inflamed state. — B. B. The ruptured mesentery, 

 forming a sort of ligature, twisted round the gut so tightly as to occasion death. 

 — C. C. The ligature just mentioned, formed of the ruptured mesentery, and 

 twisted round the gut like the tendril of a vine. — D. D. The aforesaid ligature 

 separately represented, together with its capreolus or tendril, composed of two 



bable cause of the inverted order in the measures of the degrees. Hence also most other measured meridians 

 will be erroneous, especially in the parts near seas, or near large mountains. And that insular situations 

 must be worst of any, having the plumb line deviating to the north at the south end of the land, to the 

 south at the north end, to the east at the west side, and to the west at the east side ; thus producing errors in 

 all observed latitudes and longitudes. But suffice it, at present, just to give the hint of a probable cause of 

 such errors and aberrations. 



