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disease are communicated by drains and sewers from 

 house to house, and that untrapped or badty trapped ones 

 are far worse than having no drains at all. 



"On a new Theory explanatory of the Phenomena exhi- 

 bited by Comets," by David Winstanley, Esq. 



An explanation of the phenomena exhibited by cometary 

 bodies seems to have been generally sought for amongst the 

 most hidden of nature's operations, indeed inventors of 

 theories would appear to have taken it as an axiom that the 

 extraordinary and imposing aspects which are frequently 

 presented by the heavenly bodies in question can only be 

 explained by the operation of natural laws which here we 

 do not know, by the existence of chemical substances which 

 here we have not got, or by the presence elsewhere of con- 

 ditions which here we do not find. To me it does not seem 

 that the causes of cometary appearances are of necessity 

 deeply hidden, nor that the invention of new natural laws, 

 new chemical substances or new conditions of matter offers 

 us a more philosophical or even a more handy means of 

 accounting for those appearances than without them we 

 already possess. 



It is undoubtedly in the presence and the configuration 

 of their tails that we recognise the greatest visible differ- 

 ences from the planets which comets exhibit. But these 

 visible differences curious and interesting as they are when 

 present are sometimes wholly wanting, ofttimes merely 

 rudimentary, and when existing are continually altering 

 their dimensions and their forms. There are, however, two 

 points in which comets constantly differ from the other 

 members of our system, and these points are to be found in 



