512 PHILOSOPHICAL TRANSACTIONS. [aNNO ] 67O. 



ally if we used the following expedient, (which I found the best of those I tried) 

 namely, that when the eye perceived little white specks that looked like mites, 

 the receiver should be so turned and returned, that the bellies and feet of those 

 little creatures were uppermost, notwithstanding vi^hich they would not easily 

 drop down, but continue their motion; which specks being made upon the 

 concave surface of the thin glass itself (to which you may approach your eye as 

 much as you please) are thereby rendered much more easily visible. But I pro- 

 ceed to take notice, that in the newly mentioned receiver the mites did, by 

 stirring up and down, continue to appear alive for two or three days after, if not 

 longer. I should not, I confess, have thought it ridiculous to suspect, that the 

 mites which at first lost their motion, did at last really die, and that those I 

 after saw stirring up and down, were others newly generated \n the included 

 mouldy cheese; but I was not apt to think this suspicion probable, not only be- 

 cause of the extreme difficulty of making any living creature to be generated in 

 vacuo Boyliano, but because it did not seem agreeable to what I elsewhere noted 

 about the way and time of the propagation of mites, whose eggs I have several 

 times observed with pleasure, that at a season of the year which was unfavour- 

 able (for these things happened in a cold March) newly generated mites should 

 in two or three days grow up to their just bigness, which several of those we 

 observed seemed to have attained. 



4. But because it doth not by the third phenomenon appear, whether or no 

 in case our mites had been kept in a motionless state for a much longer time 

 than three or four hours, they would have been recoverable by the admission of 

 the air, I shall add, to satisfy that doubt, that one of the portable receivers 

 above-mentioned, being exhausted and carefully secured from the regress of the 

 air, was kept from Monday morning to Thursday morning, after all which time, 

 our attentive eyes being unable to discover any signs of life among the included 

 mites, the air was let in upon them, and after no long time, had such an ope- 

 ration upon them, that both I and others could plainly see them creep up and 

 down in the glasses again. 



Jn Account of two Books. N° 63, p. 2057. 



I. Tracts written by the Hon. Robert Boyle, about the Cosmical Qualities of 

 Things; the Temperature of the Subterraneous and Submarine Regions; and the 

 Bottom of the Sea ; together with an Introduction to the History of Particular 

 Qualities. Oxford, 1670, in 8vo. 



The main design of the noble author in these, as well as his other physical 

 writings, is, to provide still more and more materials for the History of Nature. 

 He prefixes to these tracts an introduction to the History of particular Qualities^^ 



