DAMPNESS NEAR WOODS. 39 



«f conflicting theories, we study the facts separately and apart^ 

 we may find that, when all is done, there are no conflicting views to 

 reconcile ; and this I shall endeavour to do, stopping at any point 

 when lack of information renders further advance hazardous. 



Shot. I. — On the H^imidity of the Atmosphere in the Vicinity of Trees, 



indicated by the Dampness of Houses overshadotved by Trees, 



or situated in close proximity to a Wood. 



It is matter of common observation that houses closely surrounded 

 with trees are damp. Oftener than once have I heard a sufierer from 

 rheumatism told. You must get your husband to cut down that tree 

 overshadowing the house, or you will never be well. 



There may be nothing injurious in damp itself, but in evaporation 

 damp induces cold, and cold may be injurious to the human frame ; 

 damp, moreover, is conducive to the decomposition of dead organic 

 matter; the products of vegetable decay or decomposition tend to 

 produce ague, intermittent fever, rheumatism, neuralgia, and tooth- 

 ache ; and in the absence of appliances for determining the hygro- 

 metric condition of the atmosphere, the frequent occurrence of such 

 maladies may be considered indicative of the existence of the moisture 

 to which reference is made. 



With the information which has been produced, one need not be 

 surprised at the dampness of houses so situated. With evaporation 

 going on continuously, from stomates so numerous in every one of 

 such a multiplicity of leaves, the quantity of moisture in the air must 

 be much greater than it is in an open space ; and though the 

 temperature may be such as to keep it suspended in solution, an 

 affinity for moisture in the material of which the house is built will 

 attract it thence and keep the walls, and the apartment within, damp, 

 or at least less dry than otherwise they would have been. 



The quantity of moisture which clay, bricks, and granite, and other 

 forms of stone can retain in their structure, while to touch and to si»ht 

 they appear to be dry, has been ascertained, and it has been found to 

 be great ; and some of them not only retain moisture, but |absorb 

 moisture from the atmosphere. I know a noble mansion uninhabit- 

 able in consequence of the dampness produced by this property of the 

 stone of which it is built. I have known a wall to be kept constantly 

 damp through the attraction of moisture from the atmosphere by the 

 sand employed in the manufacture of the mortar; and I do not 

 recollect of ever seeing a house, built of unburnt brick, perfectly dry, 



