91 
1879.] L. Schwendler— On Electric Liyht Measurements. 
V.— Routine ; difficulty of manipulation and superintendence. 
Only one man is actually required in eacli station, to take charge of 
the steam engine, dynamo-electric machine, lamps and reflectors. 
This man should be of a rather high intelligence to be able to under¬ 
stand the working of the system, the adjustment of the dynamo-electric 
machines and lamps. 
He should be a skilled mechanic in order to he able to execute the 
necessary repairs. 
A simple Test-Galvanoscope is to be used to gauge from time to time 
the efficiency of the dynamo-electric machine in producing a current 
through an external resistance equal to one unit. 
APPENDIX I. 
General Specification of a Dynamo-Electric Machine 
required for use in India . 
(East Indian Railway). 
The dynamo-electric machine to be of the same size and pattern as 
the one manufactured by Messrs. Siemens, Brothers, of London, under the 
name, “ Medium sized,” and which in my report has been called A. 
The following alterations of the present construction are to be made : 
1. The induction-cylinder to be wound with twelve separate sections 
of wire, instead of with six, as at present. 
2. The commutator, therefore, to consist of twenty-four copper 
plates, instead of twelve, as at present. 
3. The diameter of the commutator to he increased in the propor¬ 
tion of 3 to 4 at least. In all other respects to be, however, of exactly 
the same construction as the present one, which from a construction point 
of view is perfect. 
4. Number of brushes, four, as at present, with the difference that 
they should consist of several layers of finer wire instead of one layer of 
thick wire as is the case at present. 12 sets of brushes are to be issued 
with the machine in question. 
5. The present adjustment of these brushes (with reference to 
pressure on the commutator, and relative position to the poles of the 
electro-magnet) wants some improvements. 
It is required for a safe and regular working of a dynamo-electric 
machine that the adjustment of the pressure of the brushes against the 
commutator should not only he more handy, but also finer, and that the 
adjustment for finding approximately the neutral line of the commutator 
should be made more convenient and finer. The proper practical fulfilment 
of these two conditions is of paramount importance, and if the present 
