Of OXFORDSHIRE, up 



help of that exquifite contriver, Mr. Robert Hook, commonly 

 called the Air Fump ; fo different a thing from the Injirumentum 

 Magdeburgicum, devifed by Otto Gericke x , an ingenious Conful of 

 that Republic^ that it can fcarce be reckoned an improvement of 

 that, but a new Engine ; although it muft not be denyed but the 

 Magdeburg Experiment gave occafion to its Invention. By the af- 

 fifta nee whereof, that Noble Philofopher hath accuratly examined 

 the Elafiical power ', preffure, and weight ; expanfwn and weakpefi 

 thereupon, of this element ; and thereby found out fo many 

 things neve, relating to the height and gravity of the Atmofphere, 

 nature of a Vacuum ; Flame, and Excandefcence of coals, match, 

 firing of gun-powder ; propagation of ' founh, fluidity, light, freez- 

 ing, reffiration, (yc. that to give an account of them all according 

 to the merits of the Experiments , would be to tranferibe the 

 whole Treatifeof that Honorable Author fet forth on this fubjeft ; 

 whither I refer the Reader for further fatisfa&ion, and fo to the 

 reft of his Works upon feveral other fubje&s ; many of his nume- 

 rous inventions and improvements, wherewith he has fo highly ob- 

 liged the World, having been made in this place. 



34. W hereof I (hall mention no more (it being indeed uncer- 

 tain as to moft of them, which were made here, which at London, 

 and which at other places') only the Barometer, a well known In- 

 ftrument, alfo invented here by the fame Noble Per/on, whereby, 

 the gravity of the Atmofyhere has been daily obferved by the Reve;- 

 rend and Learned Dr. John Wallit, for about fix years together : 

 in all which time he found the Quick-filler in the Tube, never to 

 afcend much above 30 inches, and never to defcend much be- 

 low 28, which he takes to be the whole latitude of its variation. 

 He alfo obferved, for moft of that time, the temper of the air 

 by a Thermometer, whereof he has ftill the Notes by him, which 

 are very particular for every day. 



35. Which latter infirument, though of very ancient inven- 

 tion, there having been one of them found by Robert de EluRibws 

 graphically delineated, in a MS. of 500 years antiquity at leaft y t 

 yet it has ftill received other ufeful advancements (befide that a- 

 bovemention'd) from that curious Artift Sir ChrifiopherWren, 

 who finding the ufual Thermometers not to give fo exaft a meafure 

 of the airs extenfion, by reafon the gravity of the liquor as it 



* Cafp. Schotti Magia Univer.part. 3. lib. 7. cap. 6. t Mofaical Philofophy; lib. 1 . cap. 1 . 



ftands 



