Memoir vpon the compound and simple Eyes of Insects. 183 



this question. Dr. Thomson, a respectable chemist, I believe, 

 but (as far as his History of tiie Royal Society, and his ill-judged 

 interference in this business, furnish evidence) a man of very 

 moderate mathematical and philosophical attainments, affirms 

 that '• the point can only be settled by repeating the observa- 

 tions." The Chevalier Delambre, the most excellent theoretical 

 and practical astronomer now living, is of a different opinion. 

 Whether your scientific readers will concur in sentiment, on this 

 purely astronomical inquiry, with the chemist or the astronomer, 

 it is not difficult to predict. 



When a writer has rendered himself Hotorious for assuming an 

 air and tone of superiority and infallibility in all his controversial 

 productions, which ill accords with his palpable mediocrity of 

 talent and knowledge ; and when he is indiscreet enough to 

 libel a whole class (and that class comprehending such men as 

 Archimedes and Newton and Laplace) for the sup))osed mistake 

 or misconduct of an individual ; it would neither be ungenerous 

 nor unjust lo lower his pretensions, and completely expose his 

 numerous blunders. But it is a task which, however beneficial 

 it might be to the public, and however easy of accom^^lishment, 

 has no fascinations for me. Dr. Thomson's other observations*, 

 therefore, not bearing upon the main question, 1 leave to sink 

 by their own weight ; and remain, 

 Sir, 



Yours respectfully, 

 RoyalMilitary Academy, Woolwicli, OlinthUS GrEGORT. 



Septe'mijer 6, 1814 



XXX. Memoir upon the comt^ound and smooth or simple Eyes 

 of Insects, and on the Manner in which these two Species of 

 Eyes concur in Vision. By M. Marcel de Serres, Pro- 

 fessor of the Sciences in the Imperial University. 



[Continued tVoni p. 118. j 



J. HE tunic of the cornea is generally black in the coleopterce : 

 it is the same in those which want the choroid a7id the mucous 

 varnish. The colour of this tunic is on the contrary much more 

 variable among the orthopterce, and sometimes one and the same 



* Such, for example, as the reasons he assigns, why tlic first two vDlumes 

 of " The TrigcriDmetrical Survey," which were actually |irihied and pub- 

 lished in Ti)e I'hih)sopliical Transactions, were not iidmUtfd into that work. 

 O exquisite pinlosoplier! to amuse and satisty hnnself uitii accounting for 

 the non-appearance of a phainoinenon in a certain phice, whfh did, not- 

 willislandirii;, appear there permamnf/i/ .' .should I ever ai^ain be involved 

 in controversy, may I iiave the good fortune to nicct with such anotlier 

 e^iponent ! 



M 4 eye 



