Mr Coddington's Treatise on the Reflection of Light, 359 



showing the connection of the vegetable productions with the soil, and their 

 geographical distribution, and it adds a value to the botanical catalogue 

 which it would not otherwise possess. We trust that Dr Johnston will be en- 

 couraged to go on with the second volume, and illustrate the Cryptogamic 

 botany of the district with equal success ; and we cannot help expressing 

 the wish that this work, and others to which it will probably give rise, 

 may excite a love of the science among that class of our gentry whose re- 

 sidence in the country gives them such excellent opportunities for its culti- 

 vation ; and we strongly recommend it to the young botanist, as a valuable 

 guide to a most delightful study. 



IV. — A Treatise on the Reflexion and Refraction of Light y being Part I, of 

 a System of Optics. By Henry Coddington, M. A. F. R. S. Fellow 

 of Trinity College, and of the Astronomical and Cambridge Philosopical 

 Societies. Camb. IS'29. Pp. 296, and 10 Folding Plates. 



Mr Coddington is already favourably known to the scientijSc world by 

 an " Elementary Treatise on Optics," which was published in 1 823. The 

 present treatise is on an enlarged plan, and is intended to introduce the 

 reader to those important theories which have lately extended the bounda- 

 ries of optical science. Mr Coddington has executed this work with great 

 ability, and it cannot fail to prove an acceptable manual to the mathemati- 

 cal student ; but we fear that the formulae are not presented in such a 

 form that the practical optician, or those who have only a small portion of 

 mathematical learning, will be able to derive any advantage from them. 

 The following are the subjects treated of in this part : — 



Introduction. On light in general, and of photometry. 



Chap. I. Reflexion of light — Combined reflexions at plane surfaces. 



Chap. II. Refraction of homogeneous light — combined refractions — 

 pri«m — lens — refracting spheres — combined lenses. 



Chap. III. Refraction combined with reflection. 



Chap. IV. Images. Vision in mirrors, or through lenses. 



Chap. V. Caustics. 



Chap. VI. Chromatic dispersion of light. 



Chap. VII. Atmospheric refraction. 



The chapters which treat of achromatism, and the spherical aberration 

 of eye-pieces, contain the substance of Professor Airy's valuable papers on 

 these subjects which appeared in the Cambridge Philosophical Transac- 

 tions ; and as this eminent mathematician communicated to Mr Codding- 

 ton the results of his unpublished researches, these difficult branches of the 

 subject are treated wifh much ingenuity and talent. 



If this work should meet with the approbation of the scientific world, 

 Mr Coddington intends to devote the next year to the subject of optical 

 instruments, and he has requested the communication of '* any hints with 

 regard to the real pr.ictical difficulties or requisites of persons engaged in 

 the use or construction of them." 



W"e look forward with high expectation to this part of our author's 

 labours ; and we trust that he will render it accessible to the practical op- 

 tician. 



