VOL. XVI.] PHILOSOPHICAL TRANSACTIONS. 307 



8. And lastly, Why, near the equinoctial, as at Barbadoes and St. Helena, 

 there is very little or no variation of the height of the barometer ? This re- 

 mark, above all others, confirms the hypothesis of the variable winds being the 

 cause of these variations of the height of the mercury; for in the places above- 

 mentioned, there is always an easy gale of wind blowing nearly on the same 

 point, viz. E.N.E. at Barbadoes, and E.S.E. at St. Helena, so that there 

 being no contrary currents of the air, to exhaust or accumulate it, the atmo- 

 sphere continues much in the same state: however, on hurricanes, the most 

 violent of storms, the mercury has been observed very low; though this is but 

 for once in two or three years, and it soon recovers its settled state of about 

 29-^ inches. 



One principal objection against this doctrine may be, that it supposes the air 

 sometimes to move from those parts where it is already evacuated below the 

 equilibrium, and sometimes again towards those parts where it is condensed 

 and crouded above the mean state ; which may be thought contradictory to the 

 laws of statics, and the rules of the equilibrium of fluids. But if we consider, 

 that when once an impetus is given to a fluid body, it is capable of mounting 

 above its level, and checking others, that have a contrary tendency to descend 

 by their own gravity, this will no longer be regarded as a material objection ; 

 but shall rather conclude, that the great analogy between the rising and falling 

 of the water on the flux and reflux of the sea, and this of the accumulating 

 and attenuating of the air, is a great argument for the truth of this hypothesis. 

 For as the sea, opposite the coast of Essex, rises and swells by the meeting of 

 the two contrary tides of flood, of which the one comes from the S. W. along 

 the English channel, and the other from the north ; and on the contrary, sinks 

 below its level on the retreat of the water both ways, in the time of ebb ; so it 

 is very probable, that the air may ebb and flow after the same manner ; but by 

 reason of the diversity of causes, by which the air may be put in motion, the 

 times of these fluxes and refluxes are purely casual, and not reducible to any 

 rule, as are the motions of the sea, depending wholly on the regular course of 

 the moon. 



A free Inquiry into the vulgarly received Notion of Nature. By the Hon. R. 

 Boyle, Esq. Anno l686, 8vo. N° 181, p. 11 6. 



This work is divided into 8 sections. In the 1st section, after having pre- 

 mised something of the manner of conception in the rational soul, the author 

 answers two objections, showing, that it is not blamable to oppugn nature 

 after this manner; and that there is sometimes a necessity to recede from the 

 common opinion of men. The 2d section reckons up the several common 



K R 2 



