VOL. XIV.] PHILOSOPHICAL TRANSACTIONS. 8() 



A Letter from Mr. John Flamsteed, concernijig the Eclipses of Jupiter s SaleU 

 lites for the Year following l685, with a Catalogue, &c. N° 1 65, p. 760. 



This is another of those predictions of the eclipses of Jupiter's sateUites, 

 which Mr. Flamsteed was in the practice, for several years past, of announcing 

 in this way after the manner of an almanack, containing a list of the times, 

 nearly when they might be expected to happen in the year following; that 

 astronomers might be apprised of the times when to prepare for observing 

 them more accurately. 



On the Effects of the great Frost on Trees and other Plants, Anno l683. By 

 Mr. Jacob Bobart. N" l65, p. 7QQ. 



Nothing seemed more surprising, though generally known to be true, than 

 the cleaving or splitting of trees in the severe frost of 1683-4. — Not only 

 oaks, but other trees were also cleft, as elms, and ash of considerable bulk and 

 value; also walnut-trees in several places suffered by this calamity. Yet oaks 

 were most of all affected, some being rent in such a manner as to be seen 

 through, and with a noise like the report of a gun. Which clefts were not 

 only to the same point of the compass, but sometimes on one side only, some- 

 times on two, three, or four several places, dividing or quartering the tree, and 

 sometimes quite through. Also, not only in the bodies, but continued into 

 the larger boughs and limbs of the tree, and sometimes descended into the 

 superficial roots, but not to those very deep in the earth ; the frost, though 

 severe, not reaching considerably deep; but several shallow roots so knotted 

 and knurled as not to be wrought upon with beetle and wedges, are known to 

 be cleft by the frost. And it is much to be suspected, whether any of such 

 cloven trees can be so perfectly sound timber, if proved by the saw and axe, as 

 they ought to be; for if so, all might equally suffer, the air having alike access 

 to one as well as the other. Whatever it was that gave occasion to some only, 

 might prove a matter worthy of enquiry. A great part of the cause is supposed 

 to be some imperfections in such trees, and the large sap-vessels and unnatural 

 cavities therein, which some call wind shaken. 



But by what means soever this may happen, it is certain that some trees are 

 much more sound than others, and that some prove full of inbred diseases and 

 cavities, before they are cut down, which cavities and stretched vessels being 

 filled with too great a quantity of aqueous and undigested sap, are thereby ren- 

 dered capable not only of condensation but freezing also ; which being suffici- 

 ently known to employ more room in the state of ice than when formerly 

 liquid, might probably cause these breaches. 



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