( <5 ) 
The ingetiiogs Author propofes, in the Sequel of this 
Work, to give an Account of new Plants only, or at 
ieaft fucli as have not been well figured by others : If 
he proceeds with the fame Exadnefs, as I don’t doubt 
he will, the Work very well deferves Encouragement j 
for of Plants thus figured and defcribed, there can be 
no future Doubjts. 
Happy had it been for us, had the Antients left fuch 
Types or Defcriptions of • thofe they recommended as 
confiderable for their Ufe inMedicine. This would have 
faved the Learned World much Labour and Study in 
an Enquiry, which ’tis to be feared, for wa^t of fuch 
Helps, will prove unfuccefsful. 
lU. At} Attempt to folve the ^hjenomenon of the 
^ife of Vapours^ Formation of Clouds and Vefcent 
of (I(ain, In a Letter from Cr. J.T. Defaguliers^ 
L T. D. K 3^. 5. to Dr. Rutty, Seer. 
/SIR, 
T H E Reafon of my writing upon a Subjed which 
has been fo often treated of,* is, that none of the 
Accounts ^ hitherto given’ of this Phenomenon (at lead 
that: 1 have met wkh) feem to me fufficient to folve all 
the pircumdances of it. 
Dr. Niewentyt and fome others fay That Parti- 
cles of Fire feparated from the Sun-jBeams, by adhering 
to Particles of Water, naake up Molecule, or fmall Bo- 
dies fpecifically lighterman Air, which therefore, by 
hydrodatical Laws, itiud rife and form Clouds that 
remain fufpended when they are rifen up- to fuch an 
Height 
