TO CORRESPONDENTS. 



J. Spence. The flax seed chaflF probably occasioned the death of 

 the cattle by accumulating in the stomach, or some other part of 

 the alimentary canal. We do not find either prussic acid or Strych- 

 nine in it, indeed it would be very strange if they were there. We 

 have not examined for other poisons. No doubt had the cattle been 

 opened soon after death its cause would have been found as above 

 suggested. Was the chaif designedly fed to the cattle ? We 

 should think it contained about as much nutriment as a mixture of 

 chips and sawdust. 



J. L. M. — A good achromatic object glass of three inches clear 

 aperture costs from forty to fifty dollars. A very passable one, 

 however, may be purchased of McAllister & Brother, Chest- 

 nut St., Philadelphia for twenty-three dollars. Eye pieces, from 

 two to five dollars. McAllister's priced catalogue is sent to all 

 who apply. 



L. A. — As the moon always presents thesmne side to the earth, it 

 is evident that any one viewing it from a fixed point in space out- 

 side the moon's orbit, would, in the course of a lunar month, see 

 every side in turn presented toward him. If this can be accounted 

 for in any other way than by the moon making a revolution on its 

 axis in the same time it makes one about the earth, we would thank- 

 fully receive the information. See Vol. 1st., page 331, of this Jounal. 



R. E. S. — The Geologic formation of this region is termed the 

 old or lower Silurian. Its fossils are shells, corals, and trilobites. 

 Shells belong to that branch of the animal kingdom termed mollusca, 

 corals to the articulata. Not a single vertebrate animal, not even a 

 fish, has as far as we know, been found in it. 



288 



