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VIII. — 1. On the Influence of Water on the Temperature of Soils. 
2. On the Quantity of Rain- Water and its Discharge by 
Drains. 
Bj JosiAH Parkes, Consulting Engineer to the Society. 
To Ph. Pusey, Esq., M.P. 
Dear Sir, — I have at length endeavoured to comply with your 
wish to receive an account of the few experiments I made, some 
years since, on the temperature of a particular soil ; of the motives 
which induced me to enter on them ; and of the practical utility 
to which an extended series of such experiments may be expected 
to lead. 
The importance of an inquiry into the physical properties 
of different soils, and particularly into the causes affecting their 
state of heat and moisture, has been glanced at by various 
philosophers and agriculturists ; but I am not aware that a 
systematic pursuit of it has yet engaged the attention of any 
British experimentalist. Mr. Handley, in his letter to Earl 
Spencer, which preceded the formation of the Society, has cited 
certain phenomena with which, it must be admitted, we are very 
insufficiently acquainted ; and he has pointed out, as still remain- 
ing among the mysteries of nature, the action of several of her 
most energetic agents. He observes: — ''The experimentalist 
might be usefully engaged in determining the temperature of 
the earth at its surface, and to the depths accessible to the culti- 
vator; the influences exerted by heat, light, and air; how far 
they penetrate into the soil, and at what point seeds cease to ger- 
minate. The effects of different culture in promoting the ab- 
sorption and retention of caloric; the extent and operation of 
capillary attraction ; points which, hitherto much disregarded, 
evidently act an important part in hastening and perfecting the 
maturity of plants ; and the study of which appears to be at least 
as interesting to mankind as those scientific labours which have 
been exercised with so much zeal to deduce the intensity of a 
central fire from experiments showing the increasing temperature 
of the body of the globe, the deeper we bore into it."* 
1 have no pretension either to the ability or the knowledge to 
fill up these racwa in the science of agriculture ; it may appear, 
even from the following imperfect observations, that the gaps are 
still wider than those above recited ; yet I would express my 
conviction that there exist no obstacles which should discourage 
the possessor of land and leisure from entering on this unexplored 
* Letter to Earl Spencer on the Formation of a National Agricultural 
Institution. 1838. 
