From some very acnmito experiment^ made by Mr Dalton, the mean 

 annual evaporation, over the whole surface of the globe, has been esti- 

 mated at 35 inches ; this gives 94,450 cubic miles for the water annually 

 evaporated over the whole globe. tee Bain. 



EVECTION.S'^ Moon. 

 EVOLUTES of Curves. (Higman.) 

 To find the equation to the evolute. 



Let A N = , and N O /3, then may 

 the relation between a and /3 be found by 

 eliminating x and y from the equations 



/ \ 



,N 



JEx. Required the evolute of the parabola. 

 Here y* m y 



Find values of ^ and .r from the two last equations, substitute them in 

 the first, and we shall have 



.". the evolute is the semicubical parabola. 



DEVOLUTION. See Involution. 



EXPANSION of liquids and solids by Heat. See Heat. 

 EXPANSION of Water See Heat. 

 EYE, dimensions of, t$c,(Coddington.) 



The proportions of the spaces occupied by the three humours of the 

 eye vary in different animals, as may be seen frm the following Table, 

 110 



