VOL. VII.] PHILOSOPHICAL TRANSACTIONS. AQ 



his own experience; yet I judge the experiment worth repeating. And if it be, 

 as I suppose it may, found to succeed, I should think, it may proceed from a 

 want of a spring or elastic power between the plates, to force them asunder; 

 and in particular that spirit of wine is not a springy body. 



3. Whether a syphon of unequal legs will be made to run, in an exhausted 

 receiver, with water or quicksilver, at a greater height than is accountable for; 

 which though M. Huygens has tried it, I think it worth repeating in this So- 

 ciety. This when it does succeed, I take to proceed from the spring of that 

 Uttle remaining air in the receiver not quite emptied. 



4. Which seems of a like nature with the former, whether a tube of greater 

 length than 29 inches, but so immerged as to be less than so much above the 

 level, as CE, may not, if filled with well cleansed quicksilver, be gently lifted 

 up with the quicksilver in it, not only to I, as when it is unpurged, but to H 

 or D, higher than the usual standard. 



5. Which is equivalent, but more easily administered, whether if such a tube, 

 so filled, be at first so inclined, as CF, that its height above AB be less than 

 2g inches, may not be leisurely and gently erected, so as to remain full, not 

 only to the height of I, but of G or D ? 6. Whether cleansed quicksilver will, 

 in the open air, run in a syphon higher than 29 inches } 7- If not in the air, 

 whether it will so run, if the lower leg open into well-cleansed water ? 



8. Which I do principally recommend; in a tube so filled with cleansed quick- 

 silver, as to stand top-full at a greater height than the usual standard, as CD; 

 in case some part be forced out, not by admission of air, but by jogging the 

 tube, suppose as much as HD, and a stop then made; whether the rest CH, at 

 a greater height than I, the usual standard, may be made so to stand of itself, 

 notwithstanding the voidance of HD .^ For by this experiment alone, if it suc- 

 ceed, it will appear, that it is not only want of room for the subtile matter to 

 recollect itself, which hinders the suspended quicksilver from falling ; but rather 

 the want of a spring to put it in motion. If it will not succeed, I should rather 

 think the springy air makes its way through the quicksilver, than through the 

 glass. 



9. Whether cleansed quicksilver will remain suspended in an inverted tube, 

 at least a short one, and with a small orifice, though its orifice C be not immer- 

 ged in quicksilver, but either in the open air, or at least in water ? j 0. If so ; 

 then whether it will do the like, if, a little being forced out, there be some void 

 room left at the top at H D ? 



These are nice experiments, and of some difficulty; but if carefully adminis- 

 tered, may be of good use in our search after the true nature of gravity: which 

 may possibly have a greater connexion with the spring of the air, than men are 



VOL. II. H 



