Dr. HerscheV s Reviewer reviewed. 36S 



the help of the telescope. The simplest of ail simple forms 

 the reviewer will admit is that of the sphere : yet Archi- 

 medes, whon invt'stigai;ng several curious properties of 

 that solid, doubtless trnployed inaiiy reflections; and the 

 reviewer iniaht impugn ihe demonstrations of that sreome- 

 triciau as unnecessary complications, with as much justice 

 as he has done Doctor Hcrschel's proofs proceeding from 

 reflections also, both mental and optical. In short, what 

 is found in the foregoing quotation is so flimsy as to del)ar 

 all philosophical discussion, and cannot be gravely replied 

 to. 



Another of the strictures is the following : (Retrospect, 

 page 23, line 4, from bottom ; when the reviewer, speaking 

 of Dr. Herschel's essay, says,) *' We cannot consider it bv 

 any means as adding to the value of those treasures of sci- 

 ence, which have in the course of years been accumu- 

 lated in the Philosophical Transactions." The reader need 

 not be here told how much those justly celebrated voluoi'.s 

 have derived their importance by recording knowledge sup- 

 ported by rxperience as science in its best form. In reply, 

 therefore, to the passage just now quoted, we shall have an 

 opportunity of entering a little more particularly into the 

 nature of Doctor Herschel's experiments and proofs, by 

 putting a few questions to the reviewer. 



Considering the avowed importance of the subject, is it 

 not an addition to our stock of knowledge to have been 

 made acquainted with many ditferent ways of obtaining a 

 sight of these coloured rings ; not only by nuaus of glasses, 

 but of metals ? See the essay, articles ] , 2, 3. 



Is it nut an addition to our stock of knowledge to have 

 discovered and shown jliat the colours of these ditlerent sets 

 of rinffs are alternate ? (see article 14.) and to have ex- 

 plained the cause of that alternation ? See article 17. 



Is it not an adilition to our slock of knowkxlge to have 

 shown that the colour of the rings, as well a^ their size, 

 can be suddenly changed, accordmg to an invariabie law, 

 by the interposition of siiadows? (see article 15,) and to 

 have explained the cause of these ebantres > See article 18. 

 Is it not an additiiMi to our stock of knowledi;e to have 

 proved also bv experniienls, tiie fuur propositions in pages 

 47 and 46 of the essay, relating to the action of the several 

 surfaces as contributing to the formation of the coloured 

 rings ? 



is it not an addition to our stock of knowledge to have 

 shown that from a polished metalline speculum we can ob- 

 tain most beautiful coloured irises ? See aiticle 33. 



if 



