C. Abbe on the Repsold Portable Circle. 213 
The bisection of a star by a single wire presents serious disad- 
vantages in attempting observations in strong twilight on faint 
stars, and is not generally attempted. e wires are stretched 
across the end of a cylindrical tube, whose independent connec- 
tion with the axis isolates it as far as possible from the exterior 
and protecting cylinder carrying the ocular. On either side of 
the cube and clamped to it by outer plates are the two circles 
having each 8 spokes and divided silver arcs of 11 inches diameter. 
The supporting arms, whose extremities form the Y’s, branch 
