1889 Science  
SCIENCE. as the Thompson electrical balance; but. the latter is an expensive instrument, beyond the reach of the ordinary electrical engineer, and is not readily portable. Professor Ryan's invention, consisting of a method of suspension and the laying-off of a scale, renders the construction of the apparatus a matter of a few hours' labor by any fair mechanic. As in the Thompson balance, the current passes through two parallel fixed coils, and through a coil swinging between them. In the
more » ... n balance the current passes into this swinging coil through the suspension, consisting of a great number of fine copper wires, which will conduct a large current, but at the same time offers but little resistance to the movement of the swinging arm. The mounting of these wires is a very laborious operation, which adds greatly to the cost of the machine. Professor Ryan overcomes this difficulty thus. From each end of the axis of the arm a single silk thread extends upward through a hole in the hard-rubber framework above. These holes are drilled at an angle with the
doi:10.1126/science.ns-14.352.295-c pmid:17841283 fatcat:h4hk23dqezapzbs57ch2gk2fjy