Bambaut — Shape of Earth's Shadow on the Moon's Disc. 57 



I have computed the equation of the curve from the complete 

 formulae given on page 53, for the time at which the abnormal 

 shape was noticed, namely, when about four-tenths of the moon's 

 diameter was obscured. At that time we have on Jan. 28, 1888, 



<P = 45', 

 zj = 58', 



p = <T = 16', 



and I find for the equation of the curve, 



if + 0-9982 s 4 + 1-9982 y* s 2 + 3-1035 if + 3-1063 yz 2 + 2-5949 y 2 



+ 0-1887 s 2 + 0-2886 y + 0-0089 = 0. 



This curve coincides so nearly with the circle whose equation is 

 given above, that it would be quite impossible to distinguish, in 

 the case of an ill-defined object like the edge of the shadow, 

 whether it were bounded by this curve or were accurately circular 

 in form. 



F2 



