222 PHILOSOPHICAL TRANSACTIONS. [aNHO 1075, 



uin Account of a Book. N° 11 6, p. 373. 



The Planter's Manual : Being Instructions for the Raising, Planting, and 

 Cultivating all sorts of Fruit Trees; whether Stone-fruits, or Pepin-fruits, 

 with their Natures and Seasons; very useful for such as are curious in Planting 

 and Grafting. By Charles Cotton, Esq. in 8vo, London, 1675. 



Microscopical Observations. By M. Leuenhoeck. N° 11 7, p. 378. 



After drying an optic nerve, and making a transverse ^section across it, M. 

 Leuenhoeck not only observed one hole in it, but several, which made it resemr 

 ble a leathern sieve; only with this difference, that the holes in the nerve were 

 not round, no more than they were all of the same size, nor so regularly posited, 

 as those in a sieve. 



He observed the sanguineous globules, that make the blood red, were firmei* 

 and harder, when his body was much out of order; but afterwards softer, when 

 his body was in a good state of health. And he is of opinion, that those san- 

 guineous globules in a healthy body must be very flexible and pliant, to pass 

 through the small capillary veins and arteries ; and that, in their passage, they 

 change into an oval figure, re-assuming their roundness, when they come into a 

 wider space. He observed also, in the clear matter of the blood, figures of a 

 quadrangular form, which he supposes to be some saline parts. 



Optical Assertions concerning tJie Rainhow . By M. Fr. Linus. N°l]7, p. 386. 



Translated from the Latin. 



1 . Any the smallest drop of rain, illuminated by the sun-beams, emits from 

 itself a perfect rainbow, not only as to the colours, but also as to their order, 

 situation, and circular figure, very much resembling that in the heavens. 



2. For the sun-beams entering a drop, and, after two refractions and one 

 reflection, returning again from thence towards the sun, escape out of the drop 

 all coloured, and endued with the very same colours, as red, yellow, green, blue, 

 and purple, which are observed in the rainbow. 



3. These rays thus coloured, being in rain transmitted to the eye from various 

 drops illuminated by the sun, cause the vision we have of an iris. 



4. There are two rings in each drop, a larger and a smaller, endued with dis- 

 tinct rainbow colours ; the less of which is distant from the axis, or ray passing 

 through the centre of the drop, by about 21°; and the larger by 78°. But the 

 rays incident on the smaller ring, are thence reflected on the greater ; from which 

 escaping into the air, they are endued with the said rainbow colours. 



