DANA'S LETTER ON CANKER-WORMS 



true. The work of mine directly leading the mind in 

 that direction is my Manual of Geology, especially pages 

 578, 579- I should like to believe that in that statement 

 of the teachings of geological history, Thiers had found 

 a convincing argument. But it is happiness enough to 

 know that, however taught or influenced, his great mind 

 and soul reached the truth and rested in it. Thanks 

 again to you for your letter. 



" It would give us all great pleasure to see you here at 

 another meeting of our Peabody Museum Trustees. Our 

 building, I think, will have your full approval, alike for 

 its architecture and its fitness for museum purposes. It 

 has been finished and furnished without exceeding the 

 hundred thousand dollars appropriated to it by our great 

 benefactor, Mr. Peabody not even a debt of ten dollars 

 being left for the future to contend with. We hope that 

 at least by another summer we shall have the pleasure of 

 waiting on you through its various rooms." 



VII 



SEVERAL LETTERS OF DANA 

 TO THE NEW HAVEN PALLADIUM 



Fighting the Canker- Worms 



" NEW HAVEN, June 4, 1864. 



" The plague of the canker-worm is upon us, and per- 

 haps, therefore, a few words on the best mode of averting 

 the evil in the future will receive attention. 



" The use of whale oil in lead troughs may be made a 

 perfect prevention. We propose to explain the reason 

 why, and the precautions necessary for success. The 

 canker-worm, as it is called, is the caterpillar or young of 

 a kind of miller. The eggs are laid upon the trunk and 

 the branches of the trees, mainly in the autumn before 

 the ground is frozen and in the spring after it has begun 

 to thaw. The laying commences early in October and 

 becomes most active in the course of November and early 

 December, Through the winter it is sparingly continued, 



359 



