91 
so that when F lias moved to O, FA. will coincide with 01) 
and the point A with D, since AF fe equal to OD. 
Therefore the ellipse will pass through D. 
Again, as the circle OHK begins to roll from its present 
position F will be the instantaneous centre, and therefore 
the tangent to the curve at the point A will be perpendicular 
to AF, that is parallel to OD, since AE is perpendicular to 
OD. 
Therefore OA, OD are conjugate diameters of the ellipse 
of which OL and OM are the semi-axes. 
The President called attention to a paper in Poggen- 
dorff’s Annalenfor July, 1872, by H. Abich, on a fall of hail 
of a remarkable character which took place near Tiflis on 
the 9th of June, 1869. 
E. W. Binney, F.B.S., V.P., presented to the Society a 
bust of the late James Wolfenden, of Hollinwood, one of 
most noted Mathematicians of the Lancashire school, who 
was born on the 22nd June, 1754, and died on the 29th 
March, 1841. In vol. 50, p. 887, of the Mechanics' Maga- 
zine , 1849, is a memoir of the deceased, written by the late 
Mr. T. T. Wilkinson, F.R.A.S., a corresponding member of 
the Society, who states that Mr. Wolfenden was sent to a 
day school at the age of six years, but the bobbin wheel 
and loom being considered much more profitable employ- 
ment than learning to read, he was taken away after one 
week’s attendance, and the sum of three halfpence defrayed 
the expenses of his scholastic education, Those deficiencies 
were in some degree supplied by the assiduity of his grand- 
father, wdio took advantage of the intervals of leisure, 
after the day’s weaving, to instruct him in reading, writing, 
and arithmetic. From this stage Mr. Wolfenden may be 
