discover the Internal Constitution of our Earth. 89 



compression, by electrical agency or chemical affinity. With 

 every species of light our vision is equally perfect ; and, conse- 

 quently, the luminous particles must, in all cases, dart forward 

 with the same celerity, or travel at the rate of al)out 200,000 

 miles in a second. But since atmospheric air is projected in- 

 to a vacuum with the velocity of only a quarter of a mile each 

 second, the motion of light is thus 800,000 times more rapid. 

 Wherefore, the propulsive force of light compared with that of 

 air is expressed by the square of this number, or 640 billions ; 

 and hence its Modulus of Elasticity must amount to the stu- 

 pendous column of 3200 billions of miles, an extension which is 

 889 times greater than the diameter of the orbit of Uranus, the 

 most distant of the planets yet discovered. Only such surpas- 

 sing powers of repulsion would appear at all adequate to balance 

 the cumulative mass of compression, and restrain the condensa- 

 tion of our globe within moderate limits. 



We are thus led, by a close train of induction, to the most im- 

 portant and striking conclusion. The great central concavity is 

 not that dark and dreary abyss which the fancy of poets had 

 pictured. On the contrary, this spacious internal vault must 

 contain the purest ethereal essence. Light in its most concen- 

 trated state, shining with intense refulgence and overpowering 

 splendour.""* 



On the Deror of the Hebrew Scriptures^ translated Swallow in 

 t?ie English Bible. By David Scot, M. D. M. W. S. 

 Communicated by the Author. 



XIeror is the name of a bird twice mentioned in the Hebrew 

 scriptures, first in Psalms Ixxxiv. 3. " The sparrow buildeth 

 for herself a house, and the swallow a nest, where she may 

 bring forth her young, even thine altars, my God and King ; '* 

 and then in Prov. xxvi. 2. " As the bird by wandering, as the 

 swallow by flying, so the curse causeless shall not come.'' 



In this last passage the original term zippor, is translated 

 bird, which, in the other, is translated sparrow, and such is under- 

 stood to be its meaning. Asa proof that this is its true sense, 

 zippor very much resembles the chirping of a bird in general. 



