DEDICATORY LETTER. 



DEAR LADY AFFLECK, 



Having undertaken with your sanction the publication 

 of the writings of your lamented brother in a collected form, 

 I may be permitted to address to you a few observations on the 

 principles by which I have been guided in the fulfilment of an 

 act of piety to the memory of a friend of many years, whom 

 I shall ever remember with affection and veneration. 



The greater part of the writings contained in this volume 

 had previously appeared in Scientific Journals, and Keports, 

 some few in Educational Treatises. I have had no scruple 

 whatever in reprinting these works, since their publication had 

 already taken place by the author's own act or permission. 



The question of the publication of manuscripts presented to 

 my mind greater difficulty. During his long years of suffering 

 he was in the habit of dictating to his friends various speculations 

 in adaptation to their different tastes and pursuits, evidently for 

 the most part not intended for the press. A great many mathe- 

 matical investigations, which may be described as interesting 

 problems, communicated to me on numerous occasions either by 

 dictation or by letter, are in my possession. Out of these ma- 

 nuscripts I have ventured to publish only two, the one on the 

 [Retardation of Sunrise, and the other a new t Solution of a 

 Problem in the First Book of Newton's Principia. All the 

 manuscripts entrusted to me by you, classical, philological, 

 botanical, and mathematical, works of a more elaborate cha- 

 racter, I have not hesitated to include in this volume, from a 

 conviction that they will be interesting to many readers, and 



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