VEGETATION DESTROYING THE WORKS OF MAN. 203 



a more impressive illustration than in this rapid ef- 

 facement of the works of man by the agency of exuber- 

 ant vegetation, under the influence of moisture and 

 the rays of a vertical sun. Damp is said to be the 

 moth of time while it causes rapid growths, it produces 

 no less rapid decay. In dry climates, on the contrary, 

 things practically seem to last for ever, as we find for 

 instance in Egypt, where grains of wheat, enclosed 

 in the sarcophagus of a mummy, have germinated 

 after a sleep of three thousand years; and paintings 

 and gildings, executed upon plaster work, and upon 

 coffin cases, appear as fresh after the lapse of thirty 

 or forty centuries, as if they had been executed but 

 the year before. We have even seen the marks left 

 by workmen's trowels upon stucco-work remaining as 

 if the work had only just been finished. Contrast this 

 with the action of climate under the influence of damp, 

 even so far from the equator as Calcutta (latitude 

 22 33' 47 /x N.), not far from the tropic of Cancer, con- 

 cerning which Sir James Martin, in his day a high 

 authority on medical science in the Indian service, and 

 a careful observer of climatic changes, says 



"A familiar but emphatic illustration of the effect of our 

 climate may be seen in its influence on the habitations of 

 Calcutta. Constructed of the finest materials, and of such 

 solidity that in England they would endure for centuries, 

 they are here, through the destructive alternations of climate 

 alone, rendered in a score of years, or less, fit habitations 

 only for crows; in much less time indeed, they may be seen 

 reduced to a heap of rubbish, covered with vegetation." * 



Time and space oblige us in some measure to abbre- 



* The Influence of Tropical Climates in the Production of Disease, 

 by Surgeon-General Sir James R. Martin, C.B., 2nd edit., p. 57. 



