60 Notices respecting New Books. 



freely, are called diamagnetic, from dia a way ; and hence all bodies 

 in nature are now grouped under the two classes of magnetic and 

 diamagnetic." Not " hence," Mr. Hunt ; you are confusing terms. 

 The discoverer of diamagnetism happens to entertain the precisely 

 opposite view, as to the permeability of diamagnetic bodies. Ham- 

 mering does not render brass magnetic, as stated by Mr. Hunt ; the 

 magnetism is borrowed from the iron tools used in the operation. 

 " If a source of light," says Mr. Hunt, " be placed in the focus of a 

 concave mirror, there will be no image, but a brilliant reflexion in 

 parallel lines from every point on its surface." In one case only is 

 this correct, and that is when the mirror is parabolic ; but Mr. Hunt 

 is here speaking of " curved mirrors" without limitation. Again, 

 we are informed, " The image seen in a concave mirror is always 

 magnified, whereas in a convex one it is very considerably reduced." 

 Why "very considerably?" The reduction may be infinitesimal if 

 the radius of the mirror be only long enough ; where the radius is 

 infinite, there is no reduction at all. The rainbow is thus explained 

 by Mr. Hunt : " A ray of light falling upon a drop of rain becomes 

 refracted on entering the first surface ; it is reflected from the other 

 surface of this sphere, and thus emerging from a medium point, suf- 

 fers prismatic refraction ; the least refrangible rays, the red, forming 

 the inner portion of the bow ; the most refrangible, the violet, its 

 outer edge." Part of this is unintelligible, and part false. What is 

 meant by emerging from a medium point ? Mr. Hunt is here speak- 

 ing of the primary bow ; and, if he takes advantage of the next sunny 

 shower, he may inform himself that the disposition of the colours is 

 precisely the reverse of what he states it to be. Indeed, had Mr. 

 Hunt, as a general rule, trusted more to his eyes and less to his 

 fancy, we should have had a better book. 



We now close it — not for want of material for further remark, for 

 every page of the book is a comment on the incompetency of its 

 author. We regret to be obliged to state this, but the imperfections 

 of the work would justify still stronger condemnation. A recent 

 review in our contemporary, the Literary Gazette, opens with the 

 following words : — " There is an amazing quantity of bad science 

 floating in society, the result chiefly of pretence and imperfect educa- 

 tion." What hope can we have of abetter state of things, when we 

 find a man, whose knowledge of the subject is evidently inferior to 

 that of the veriest tyro, exalted, under government sanction, into the 

 position of a teacher of physical science ? 



The Calculus of Operations. By John Paterson, A.M. Albany, 

 1850. 8vo. 



How the author got the two letters which follow his name, or 

 why he lowered his pretensions so far as to adopt them, we do 

 not know. He has been his own teacher, and he is a working 

 printer ; the materials of the book are the fruit of his evening leisure, 

 and the setting of the types was done by himself. It does not sur- 

 prise us that in a country where ordinary education is widely dif- 



