1820.] Memoirs of the Literary Societij of Manchester. 193 



when the space between them was filled with water, nearly 24 ; 

 and when muriatic acid of the specific gravity 1-177 was mtro- 

 duced, the focal distance was 28 inches. 



Liquids. 



Water 



Ditto with a little acid 

 Ditto with more acid. . 

 Ditto, ditto, ditto . . . . 

 Ditto, ditto, ditto. . . . 

 Muriatic acid 



Irirlie-. 



23-75 

 25-00 

 25-70 

 26-60 

 27-00 

 28-00 



Sj) gr. deduc- 

 ed froiii focal 

 di^l;lllce^. 



1-000 

 1-053 

 1-088 

 1-121 

 1-138 

 M80 



The lenses in these experiments were made of crown glass. 

 The experiments were repeated with lenses of flint glass and 

 crown glass ; but the results were the same. On trying the 

 same experiments with nitric and sulphuric acid, he found that 

 the specific gravities increased at a much greater rate than the 

 focal distance. From this remarkable property of muriatic acid, 

 the author suggests the use of such a com.pound lense to deter- 

 mine the specific gravity of the acid. 



VII. An Essay on the Origin of Alphabetical Characters. By 

 the Rev. William Turner, Jun. A.M. — It has been pretty gene- 

 rally maintained by literary men that the first alphabet was made 

 Jcnown to mankind by Divine revelation. Dr. Hartley was of 

 opinion that it was revealed from Mount Sinai when the ten 

 commandments were written by the finger of God on two table* 

 of stone. The same notion was supported by the celebrated 

 Gilbert Wakefield in an ingenious paper on this subject inserted 

 in the second volume of the Memoirs of the Manchester Society. 

 Mr. Turner's object in the present essay is to combat this opinion^ 

 and to show that letters, like many other discoveries, not inferior 

 in difficulty and importance, may have been the fruit of human 

 sagacity properly directed. The essay is divided into two parts : 

 in the first, he endeavours to answer the arguments advanced by 

 i\Ir. Wakefield in support of the Divine origin of letters ; in the 

 second, he gives his ideas of the way in which the discovery 

 may have been made. 



Mr. Wakefield's first argument is, that the invention of letter* 

 differs in one remarkable particular from all others ; namely, that 

 -the first effort brought it to perfection. This assertion Mr. 

 Turner is disposed to deny. We have no evidence that it was 

 perfected at once. The first rude attempts would be forgotten 

 m consequence of the more perfect ones that followed them. 

 Even the Hebrew alphabet seems at first to have been very rude. 

 If the Phoenicians borrowed their writteu lar\trMa<?e from thet 



Vol. XV. N° III. 



N 



