VOL. XXVI.] PHILOSOPHICAL TRANSACTIONS. 49/ 



41616 to 52126 1 which is often observed, the greatest velocity of the blood 

 will be to the least, as 10000 is to 1. 



In his discourse on muscular motion the author proves, that the vesicles of 

 each fibre in the action of a muscle, are inflated by the rarefaction of the blood 

 and spirits within their cavities; and explains the cause of this inflation and 

 rarefaction from the principles of attraction. And then he shows, by increasing 

 the number of vesicles, and diminishing their size, the swelling of the muscle 

 may be made so little, as to be imperceptible, and the expence of spirits very 

 much lessened, and yet there will be the same degree of contraction in the 

 muscle. 



He then proceeds to determine the force of the elastic fluid, and its propor- 

 tion to the weight that is to be raised, according to the various degrees of in- 

 flation. His demonstrations here are founded on the same principles with those 

 of Mr. John Bernoulli, but are more easy, and suited to the capacity of those 

 who are not versed in the deeper parts of geometry. 



Tables of the Barometical Altitudes at Zurich, in Switzerland, in the Year 1708, 

 observed by Dr. Joh. Ja, Scheuchzer, F.R.S. and at Upminster, in England, 

 observed at the same Time by Mr. W. Derham, F. R. S. as also the Rain at 

 Pisa, in Italy, in 1707 and 17O8, observed there by Dr. Michael Angelo 

 Tilli, F.R.S. and at Zurich in 1708, and at Upminster in all that Time : 

 fVith Remarks on the same Tables, as also on the Winds, Heat, and Cold, and 

 divers other Matters occurring in those three different Parts of Europe. By 

 Mr, JV. Derham, Rector of Upminster. N° 321, p. 334. 



From the comparison of the thermometers, Mr. Derham finds that the 

 warm and cold seasons at Zurich and at Upminster, fall nearly together, the 

 changes taking place from one to five days of each other ; so that, in general, 

 what is a warm or cold month or season at the one place, is the same also at 

 the other. — As to the winds at those two places, there is but little agreement 

 among them, being oftener different than alike : but when they do agree, it is 

 chiefly when the winds are strong, and of long continuance. — As to the baro- 

 meters, the mercury was always lower at Zurich than at Upminster, by a dif- 

 ference sometimes amounting to as much as two inches; but the medium dif- 

 ference is about half an inch; from which Mr. D. infers, that Zurich is 

 situated about a quarter of a mile higher above the surface of the sea, than 

 Upminster is. 



Farther, it may be observed, that, as near the equinoctial the barometer is 

 observed to be nearly stationary, but the more the latitude, the greater the 

 range of the mercury, so at Zurich the difference was not so great between the 



VOL. v. 3 S 



