PREFACE. 



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ui arc esBentially of. 



ance which require instriimenta 

 some delicacy^ and if not executed with a certain preci- 

 sion and nicety, had much better not be recorded at all. 

 But in both thcBe cases pa: ticular care has been taken 



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to make the instnictions for the use of the necessary 

 infc^trumeots so nlain and full- that no diffieultv can be 

 experic*^"''^'i by any one in acquiring from thenis witii a 



nagcment. 



little pracucc, their perfect mar 



The time apparently contemplated in the Memorandum 

 for the completion and appearance of the work has be a 



exceeded. The delay, however 



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been inevitable 



One only of the contributors was aware^ until nearly a 





month sub^^'^^^^ent to t^^^ date of that document, of what 

 was required of him ; and the various professional and 

 scientific engagements of almost all^ precluded the possi- 

 bility of their complying on the instant with the request. 

 The Editor in particular must plead guilty to having 



been the latest in the field. The subject of Meteorology, 



intended for a far more able hand, devolved 



originally 



upon him, in consequence of the inability from illness, 

 and supervening ^-lost pre-^^-ing engagements^ of the party 



in question to ndcrtake it- His own hands were uiher 



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vdse full : and he is but too conscious that, although 

 written three or four times over^ his contribatlon fells 

 very far short indeed of whv^t would have occrp^ed its 



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