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solar spectrum has enabled us to do "what we never could 

 have done before, or imagined possible to have done. 

 There is no reason for doubting that many similar potent 

 instruments for penetrating the mysteries of Nature are 

 yet to be discovered. 



I thank you, ladies and gentlemen of the Essex Insti- 

 tute, for listening to me so patiently, and wish you all 

 success in your studies in these deeply interesting depart- 

 ments of knowleds^e. 



Mr. Richard H. Dana being called upon, after dis- 

 claiming any special knowledge of the subjects discussed, 

 sa}ing that he could make out as clear a case of ignorance 

 of scientific questions as could Dr. Chirke, related in con- 

 firmation of this an incident at his father's house after ho 

 had graduated. President Woolsey, who was our guest, 

 asked me if I had seen, in California, the cactus. Not 

 knowing what the cactus was, I endeavored to get over 

 the difficulty by saying that I had not been in the interior 

 where the rich lands and gardens were, but on the dry, 

 sandy seacoast. My family were somewhat disturbed, 

 they being aware, as I was not, that the cactus grew in 

 just such dry, sandy places. I then described a largo 

 "prickly pear," with its beautiful flower and blossoms, 

 which we found on the coast, and this, to my confusion, 

 was the cactus itself. 



As Dr. Clarke has said, we collegians thought moral 

 science the only important study. After graduating at 

 Harvard I thought of taking a course in philosophy with 

 Professor Marsh, at Burlington, Vt. He asked me what I 

 kncAv of natural science. I told him, nothing. To teach 

 moral and intellectual philosophy thoroughly (he said) 

 there must be a ground-work of the natural sciences. The 

 aying of this foundation, I found, would take too much 

 time, and I did not attempt his comprehensive course. 



