1847.] Blight. 129 



The foregoing is merely a catalogue of rocks arranged on the 

 one side by the late Professor Eaton, and on the other as they 

 have been determined by the late surveys. The existence of the 

 old red sandstone in this state was pointed out by Dr. James 

 Eights in one of the early numbers of the Zodiac. 



As it regards the order of the rocks, all that is necessary seems 

 to be determined. Many rocks are named in this list, which are 

 really only subordinate masses, and yet it was proper they should 

 be described. 



In Mr. Eaton's arrangement, it will be observed that all the 

 rocks denominated secondary class, are placed above the old red 

 sandstone, the rock which forms the Catskill mountains, and was 

 correctly called old red sandstone. This great error arose from 

 the error already referred to; that of regarding thesaliferous rock 

 as the new red sand stone of Europe, which, in the old classifica- 

 tion belonged to that class. It led to the strange result, that of 

 blinding the eyes to the actual superposition of rocks, which to 

 present observers is perfectly clear. 



BLIGHT. 



This disease, the description of which has occupied several 

 pages of the present number of this Journal, is not usually well 

 dehned. As commonly applied, it designates any kind of disease 

 which affects fruit trees, and terminates in the curling up, or destroy- 

 ing their leaves and blossoms. It is also applied to those changes 

 in leaves which amount only to a sickly appearance, as well as 

 to another affection peculiar to the black plum; the black warty 

 excresence of the branches. It is plain enough, that there is much 

 error in the application of the term, inasmuch as it embraces seve- 

 ral diseases which are quite different from each other, — even the 

 attacks of insects as the leaf rollers, and the different species of 

 Aphis, produce what some regarded as the blight, though with- 

 out reason. 



The term Blight in our opinion ought to be confined to that pe- 

 culiar disease which is produced by atmospheric influences. We 

 do not mean by this expression that there are certain flying va- 

 pors in the atmosphere which are concentrated upon certain parts 

 of a plant, and which operate like a burning glass. To effect a 

 blight in plants it seems only necessary that their parts should be 

 in a juicy suculent state, and growing rapidly. This state is 

 common to pear and apple trees planted in rich and highly ma- 

 No. 17. 9 



