66 PHILOSOPHICAL TRANSACTIONS. [aNNO l66d. 



by Mr. Hook, on the planet Mars ; in the face of which he affirmed that he 

 had discovered, in the late months of February and March, that there are 

 several maculae or spotted parts, changing their place, and not returning to the 

 same position till the next ensuing night, near about the same time. Whence 

 it may be collected^ that Mars, as well as Jupiter and the Earth, &c. revolves 

 about his own axis. 



Preserving of Birds talten out of the Egg. By Mr. Boyle. 



A^" l!2, p. 199. 



In order to observe the process of nature in the formation of a chick, Mr. 

 Boyle opened the eggs at different periods after incubation, and carefully taking 

 out the embryos, embalmed each of them in spirit of wine in a distinct glass 

 carefully stopped. 



In making these experiments some circumstances are to be observed ; one 

 is, that there be generally mixed with the spirit of wine a little spirit of sal 

 ammoniac. The other, that it is proper to put the foetuses for some time in 

 ordinary spirit of wine, to wash off the looser filth, and then let them soak in 

 the same kind of spirit or better, that the foetus, being removed into more pure 

 and dephlegmated spirit of wine, may not discolour it. 



Of an unusual Method of propagating Midherry Trees in Virginia* 



N' 12, p. 201. 



I have planted ten thousand mulberry trees, and hope within two or three 

 years to have good silk by this means. My method, which is uncommon, 

 accelerates their growth two or three years sooner than if they were sown in 

 seed. I intend likewise to plant them as thick as hedges, like currants or 

 gooseberries. By this method they will always be young tender plants, and be 

 easily cut in great quantities with a pair of garden-sheers, whereby one man 

 may gather as much as four could do when they are in trees at distance from 

 each other. But possibly the best way would be to sow some acres with mul- 

 berry seed, and to cut them with a scythe, and thus keep them under ever 

 after. 



To make a Glass of a small Plano-convex Sphere, to refract the Rays 

 of Light to a Focus at a greater Distance than usual. By Mr. Hook. 

 N' 12, p. 202. 



Prepare two glasses, the one exactly flat on both sides, the other flat on one 

 and convex on the other, of any sphere you please. Let the flat glass be a little 



