VOL. XXXV.] PHILOSOPHICAL TRANSACTIONS. 2/1 



according to Mariotte, it is only 10° 3' or 63 feet; and Cassini supposes it only 

 at 10° or 60 feet. 



In like manner, the height of the atmosphere, from IB" to 27" I V", is found 

 to be 64' 9" 2'". According to the same rule, half the height of the atmos- 

 phere, that is, the height of the place, where the mercury in the barometer 

 would descend to 14 inches, appears to be 1506o' 3", or 2510° O' 3". Still 

 upon the same principle, the mercury will descend to one line at the height of 

 133,397 Paris feet above the level of the sea, which make 22,232 toises 5 feet, 

 or 1 1 Paris miles (at 2000 toises the mile) 232 toises 5 feet. But as, in order 

 to determine the whole height of the atmosphere, the logarithm of ]'" ought 

 to be deducted from the logarithm of 336'", or 28"; and as that logarithm is 

 00000, it follows from thence, that beyond the place where the mercury would 

 descend to l'", the air is expanded into an indefinite space. 



Observations on the difference of Sex in Misleto.* By the Rev. Mr. Edm. Barrel. 

 N°405, p. 547. 



Mr. Barrel having mentioned being pretty certain, that the plants of misleto 

 were some of them male and some female; he was afterwards informed that Dr. 

 Boerhaave had already told the world of a difference of sex in' misleto. But 

 having, since that, seen the Historia Plantarum, which is published as of his 

 dictating; he found that he mentions it in such a manner as makes it seem that 

 he only took his notion from Tournefort, and was not fully apprized of the 

 true nature of these plants : ovarium alio a flore loco natum seems to suppose 

 both flower and ovary to be on the same plant, though in distinct places 

 of it. 



Mr. Barrel had, from his own sowing of the berries, 4 thriving plants of 

 misleto growing on one tree in his garden. These, being often in his view, 

 gave him the first apprehension of there being any difference of kind or sex in 

 this shrub. They were not of age to bear flower or fruit till 1726, when one 

 of them bore a berry or two; and expecting that they should all do so the fol- 

 lowing year, he frequently examined them, and found that two plants had 

 berries, and two had none. He then went and examined the misleto on other 

 trees, which have plants of above 20 years growth. And he found the method 

 of nature to be thus. 



Dr. Grew observes, that many plants make a visible preparation in the former 

 year, for the flower and fruit of the next season. This is done also by misleto. 



* The misleto belongs to the class Dioecia in the Linnaean system, in which the male and female 

 (lowers stand on distinct or separate plants ; its order is that of Tetrandria. 



