360 Observations made on a Botanical Excursion. [Oct. 



whom I am exceedingly obliged for the prompt and kind manner in 

 which he has afforded me effectual assistance in various ways. 



The Dew-point has been calculated from the Wet bulb, by Dr. 

 Apjohn's formulae, or, where the depression of the Barometer is consi- 

 derable, by those as modified by Captain Boileau.* The saturation 

 point, by dividing the tension at the dew point by that at the ordinary 

 temperature. Weight of vapor, by DanielPs formula. 



For the means of availing myself of Mr. Williams' kind invitation, 

 so soon after my arrival in India, I am mainly indebted to the President 

 of the Asiatic Society, who not only anticipated my wants by himself 

 equipping me for a mode of travelling widely different from what I had 

 been accustomed to, but has forwarded my views by every means in his 

 power, and shown the warmest interest in my pursuits and kindness to 

 myself. Darjeeling, Aug. 1848. 



My botanical outfit was all procured for me at the Botanic Garden* 

 by the kindness of Dr. McLelland, to whom I return many thanks for 

 the valuable assistance and advice he afforded me, and the ready manner 

 in which he placed every aid the noble establishment he then super- 

 intended could command, at my service. 



January 30th. — Joined Mr. Williams' camp at Taldangah, on the 

 Grand Trunk Road, a dawk station near to the western limit of the 

 coal basin (Damoodah valley). 



Leaving early the following morning, I had no opportunity of in- 

 specting the fossil plants of this field in situ. An examination of a 

 noble collection sent to England by Mr. Williams, (previous to my 

 departure,) throws but little light on the age of the formation, as com- 

 pared with the more northern ones. The genera to which the species 

 belong are, some English, a few very remarkable ones Australian, 

 and many others peculiar to the Indian coal fields. The European 

 genera or species, are more allied in appearance to those of the Oolite 

 formation than of the carboniferous sera, bat I take this resemblance 

 to be possibly accidental, and not to demand a reference of the Indian 

 coal beds to the period of the English Oolite. Arguing from analogy, 

 it is difficult to suppose that the cotemporaneous Floras of two coun- 



* Journal of Asiatic Society, N. 147, (1844) p. 135. 



