470 MEMOIR OF DAXIEL TKEADWELL. 



all the time that you are at Brunswick. But as I said before, make the time when you see fit ; we 

 shall only insist on what you bargained for, namely, a long visit and at an early period. . . . 



I am, and have been for a few weeks, reading and mastering Bishoji Berkeley's theory of the 

 non-existence of the material world. It has been a bother to me all my life, but I have now 

 mastered the conception of it, and am well repaid for my labor. I think it is all wrong, and do 

 not believe that lie believed in it. But it is wonderfully ingenious and supported with vast 

 ability. Mrs. T.'s best regards to you, and those of both of us to Mrs. Sweetser. 



Ever truly yours, 



Daniel Treadwell. 



The following communication to tlie Boston Society of Natural History well 

 illustrates Mr. Treadwell's habits of observation, and his patient and carefully con- 

 ducted experimentation in a matter so far removed from his ordinary pursuits. His 

 reflections and their practical application are well worthy of note. 



Tlie partial report printed in the proceedings of the Society was also printed 

 in Samuel's " Book of Birds." 



0,1 the Food of the American Robin. (^Tardus migratorius, Linn.) 



On the 5th of June, 1858, when driving in the vicinity of Fresh Pond, my attention was 

 attracted by two young robins wliich liad probably been turned out of their nest by some mis- 

 chievous boy or cat. They were running rapidly by the roadside, uttering loud cries of distress. 

 As they could not raise themselves upon the wing, I had no difficulty in taking them both. 

 Tiiey were quite young; their tail feathers being less than one inch long, and, as I inferred from 

 the actual weight of one of them a few days after, I think tlicy then weighed about 25 

 or 26 pennyweights each, — less than half the weight of a full-grown robin; but they were 

 plump and vigorous. As it was evident tliat they would soon perish if left to their own 

 resources, I determined to take them home and give them a chance for their lives in a cage, for 

 a while at least, thus repaying as well as I could the obligation which two of their namesakes, 

 if not their blood relations, conferred upon the " children in the wood " in another place, and 

 many years ago. Having with some trouble provided a temporary cage, I commenced feeding 

 them with earth-worms, giving three (I have taken their weight at 12 grains each in the 

 accompanying table) to each bird, it being then near sunset. During the second day I gave 

 tliem 10 worms each, which they ate ravenously. Thinking this must be much beyond the 

 quantity of food that could be supplied by the parents in the wild state, I cut them off with this 

 allowance. On the third day I increased their food in the forenoon to 8 worms each, but in 

 tlie afternoon I found that one of the birds was becoming feeble, and it soon refused its food and 

 died. On opening it, I found its crop, gizzard, and whole intestine entirely empty, and I there- 

 fore concluded that it had perislied for want of sufficient food ; the effect of hunger being per- 

 haps increased by cold, as the thermometer was but about 60°. I therefore placed the other 

 bird, which yet seemed vigorous, in a warmer place, and increased its food, giving it in the whole 

 day 15 worms. The fourth day this was increased to 21: worms, on the fifth to 25, sixth 

 to 30, and on the seventh to 31 ; but as the cry was still for more, and as the bird 

 seemed to be losing plumpness and weight, I commenced weighing both the bird and his food. 

 The following table exhibits the amount of food consumed each day for thirty-two days, and 



