VOL. XLVII.] PHILOSOPHICAL TRANSACTIONS. 289 



through the pupilla, he has been obliged to give a snip of the scissars to the iris, 

 which he says is attended with no bad consequences. 



In answer to what is said, that it has been practised before, and that Taylor 

 formerly performed it, he endeavours to prove, that it never was, excepting in 

 cases where the crystalline had, by some accident, slipt through the pupilla into 

 the anterior chamber. In regard to the operation, there is some mention made 

 of it among the Arabians, as what they had heard of; but the operation is not 

 described particularly any where. One convincing reason, that it never was 

 carried into practice among the ancients, is, that had they made the extraction 

 of the cataracts, they must have found it to be the crystalline humour, and not 

 remained in the error they have all fallen into, that the cataract was a mem- 

 brane formed in the aqueous humour. 



In regard to Taylor, he may have attempted, but never did carry it into prac- 

 tice ; else he would not have failed to have published it in the numberless 

 productions he has given. Dr. H. knows that, in 1743, he followed him in 

 Edinburgh for 6 months, where he performed above 1 00 operations of the cata- 

 ract by couching ; but never once attempted this way, nor ever mentioned it, but 

 in the case where the crystalline is lodged in the anterior chamber ; which ope- 

 ration has been described in many authors. So that he thinks, Mr. Daviel may 

 be truly said to be the first, who had brought this method into general practice 

 for the cure of a cataract. 



Dr. H. thinks, the greatest risk one runs in this operation, is the pushing out 

 of the humours of the iris through the opening, which forms a staph)loma ; and 

 he finds this has been the case in some of those that have failed ; and it is not 

 easy to contrive a bandage on that part, to make a compression equal to the re- 

 sistance of the cornea before it was opened. 



XCI. Letters of the Abbe Mazeas, F.R.S. to the Rev. Stephen Hales, D.D., 

 F.R.S. on the Success of the late Experiments in France, concerning the Ana- 

 logy of Thunder and Electricity. Translated from the French by James 

 Parsons, M.D., F.R.S. Letter 1, dated St. Germain, May 20, 1752, N. S. 

 p. 534. 



The Philadelphian experiments which Mr. Collinson communicated to the 

 public, having been universally admired in France, the king desired to see them 

 performed. Therefore the Duke d'Ayen offered his majesty his country-house 

 at St. Grermain, where M. de Lor, master of experimental philosophy, should 

 put those of Philadelphia in execution. His majesty saw them with great satis- 

 faction, and greatly ajjplauded Messieurs Franklin and Collinson. These ap- 

 plauses of his majesty having excited in Messieurs de Buftbn, D'Alibard, and 

 De Lor, a desire of verifying the conjectures of Mr. Franklin, on the analogy 



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