VOL. XXIV.] PHILOSOPHICAL TRANSACTIONS. 147 



with which nature has provided all these unborn animalcula, were as plainly 

 visible. 



Fig. 15, ABCDE show the body of the said animalcul urn; bh, di and dk the 

 4 legs, the 2 other being hid from the sight; ep represent one of the horns, 

 of which we had a fair view; the second horn AG was not placed in so conve- 

 nient a light, and consequently not so well delineated ; at the extremity of the 

 horns there were three small hairs, which are also seen at f and g. 



An Experiment J to show the Cause of the Descent of the Mercury in the Ba- 

 rometer in a Storm. By Mr. Francis Hauksbee.* N° 292, p. I629. 



In the late hurricane of wind, Nov. 1703, it was observable, that the Mer- 

 cury in the barometer did not only considerably subside, but on extraordinary 

 gusts a visible vibration of the quicksilver appeared. And to prove that high 

 winds can lessen the pressure of the atmosphere, an experiment has lately been 

 made at a meeting of the Royal Society at Gresham College, April the 1 2th, 

 1704, by Mr. Francis Hauksbee, giving a demonstration of this phenomenon. 

 Plate 5, fig. 16, the recipient a containing about 5 quarts, having about 3 

 or 4 times its natural quantity of air compressed in it by the syphon bb, 

 which for that purpose is screwed on at the bottom, within the side of the 

 bason c. The stop-cock d being turned, and the syphon taken off, a small 

 swan-neck pipe, e, is screwed on in its place, which fits into a brass socket, 

 which is fixed in a cubical piece of wood p, right against the horizontal pipe g. 

 From the same cubical piece f arises a naked barometer hh, whose cistern lies 

 open to the passage, which leads from the swan- neck pipe to the horizontal 

 tube aforesaid. Likewise from the same piece f, proceeds another pipe or 

 tube I, parallel to the horizon, leading to another cubical piece of wood k, 

 3 feet distant from the former : out of which likewise arises another barometer 

 LL, whose cistern is also open to the horizontal tube i, and by that means has 

 a communication with the open cistern of the other. The parts thus disposed, 

 and the stop-cock being turned, the condensed air proceeds strongly through 

 the swan-neck pipe, which discharges it into the horizontal tube g, whose cur- 

 rent so diminishes the pressure of the atmosphere on the cisterns of the respec- 

 tive barometers, as to cause the mercury to descend 2 inches at least. And it 

 is observable, that that barometer, which is 3 feet distant from the current air, 

 is equally affected, and subsides parallel with the other. It is also to be 



* Sometime Curator of experiments to the R. S. and author of Physico-Mechanical Experiments, 

 published 1709. He trod in the footsteps of Boyle j and by his experiments on electricity, he made 

 some important additions to the then comparatively small stock of fact* in that branch of natural 

 philosophy. . '-'-' -''■■■■.' r., .^ 



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