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FOREIGN SEEDS AND PLANTS. 



Thefe hints may prompt us to try the larger fucculent 

 fruits; for inftance, the mangoes, lechees, and others of 

 this kind : If their flelhy part, when they are very ripe, 

 was brought to the confiftence of raifms or dried figs, it 

 would keep their kernels plump, and in this flate they 

 might be better prcfervcd in wax, than by any oilier 

 method yet known. 



i!< : 



,'V 



An 



for the CHANGE of C 



A 



r 



nvhich has been ohfervedin the Middle Cqlomes tn North^^ 



America, By Hugh Williamson, M. D. Read be- 



fore the Society ^ Augnfi ijth-, 1770. 



T is generally remarked by people who have refided 



long in Peuniylvania and the ncighbouriag colonies, 



that within the laft forty or fifty years there has been a very 

 obfervable change of climate, that our winters are not fo 

 intenfely cold, nor our fumipers fo difagreeably warm as 

 they have been. 



That we maybe enabled to account for thefe phoenomena 



it will be neceffary to take a tranfient view of the general 

 caufe of winds, and the remarkable difference of heat and 



cold, that is obferved in difterent countries under the fame 

 parallels. 



Though the Sun is doubtlefs the general fource of heat, 



yet we obferve that countries are not heated in proportion 

 to their diflance from the Sun, nor even in proportion to 

 their diftance from the equator. The inhabitants of the 

 polar circles are hardly a perceivable diflance, not a twenty- 

 thoufandth part farther from the Sun, than thofe between 

 the tropics, yet the former are chilled with perpetual cold, 

 while the others arefcorched witli conflant heat, 



When the rays of the Sun ilrike the Earth in a perpen- 

 dicular diredion, they will be refleded in the fame direc- 

 tion on the particles of air through which they have paffecJ, 

 and thus incrcafe their heat; a greater number of direft 



rays will alio ftrike the earth many given fpace, than 

 ^ when 



