REPORT OF THE SECRETARY. 31 



law of the sun's intensity at any instant during the day. Determina- 

 tion of the sun's hourly and diurnal intensity. On local and climatic 

 changes of the sun's intensity. On the diurnal and annual duration 

 of sunlight and twilight. These are all mathematical deductions 

 from well established principles, and constitute the preliminary prob- 

 lems towards a logical solution of the phenomena of the meteorology 

 of our earth. The author offers to continue his interesting investiga- 

 tions in this line of research, provided the Institution will employ 

 a person to make the arithmetical calculations, or, in other words, to 

 deduce from the formula the numerical values of the quantities 

 required. His own time must be principally occupied in other duties, 

 though he will cheerfully devote his leisure hours to the investigations, 

 with a view of extending the bounds of knowledge. He considers most 

 of the memoirs which have been published in the transactions of 

 different learned societies as preparatory to a more complete solution 

 of the problem of terrestrial heat. He has succeeded in bringing the 

 formulre of the theory of heat in closer connexion with observation 

 than heretofore, and thinks there is now an opportunity presented 

 for increasing our knowledge of meteorology on the " theoretic side." 

 From a consideration of the interesting problems which have been 

 discussed in the memoir just published, and the manner of their solu- 

 tion, it can scarcely be doubted that valuable results will be produced 

 by an appropriation for the continuance of these researches. 



The first part of the paper on Oology, described in the last report, 

 is now in the hands of the printer. Every possible pains has been 

 taken to make the illustrations as accurate representations of the 

 objects as can be accomplished by art. The globular shape of the 

 eggs^ and the receding aspect of their markings, have heretofore 

 baffled all endeavors to represent them correctly. The best and most 

 artistic works of this kind, involving a very expensive operation, are 

 but partially successful. The desideratum has been obtained by the 

 employment of photography in making the original delineations, and 

 this has furnished an exact and available basis, which the engraver 

 can copy at his leisure, and which represents with fidelity, otherwise 

 unattainable, the appearance to be perpetuated. These improvements 

 have been made by Mr. L. H. Bradford, of Boston, to whom the en- 

 graving has been entrusted. The plates will be printed in colors. An 

 order has been received from England, in advance, for a number of 

 copies of this work, the proceeds of which will be devoted to lessening 

 the' cost of the illustrations. 



