956 REPORT—1890. 
MONDAY, SEPTEMBER 8. 
The following Papers were read :— 
1. A New Electric Meter. The Multicellular Voltmeter. An Engine-room 
Voltmeter. An Ampere Gauge. A new Form of Voltapile, useful in 
Standardising Operations. By Sir Wituiam TxHomson, D.C.L., LL.D.,— 
F.R.S. 
2. The Lineff Electric Tramway. By Gispurr Kapp. 
The conductor consists of bare copper strip or cable and of iron strip. The 
latter is galvanised so as to protect it from rusting. It lies on the copper conductor, 
and both are enclosed in a sealed channel formed of asphalt. The copper conductor 
rests upon the bottom of a trough made of a succession of glazed tiles, and the 
cover to this trough is formed by the lower flanges of iron rails arranged in short 
sections so as to be insulated from each other. The head of one rail reaches up to — 
the surface of the road, the head of the other is cut off, and this rail is therefore 
completely buried in the asphalt. The surface rail, which may be arranged along- 
side one of the ordinary tram rails or in the centre of the track, is in electric and 
magnetic contact with an electro-magnet carried under the car. This magnet runs © 
upon the surface rail on wheels which form its north and south poles. The distance 
of the wheels is greater than the length of a section of insulated rail, so that 
successive sections become oppositely magnetised. This causes the iron strip 
immediately below the magnetised region to be attracted upwards and thus come 
into contact for a length of several feet with the under side of the two sectional 
rails, At the same time the iron strip to both sides of this region remains in contact 
with the copper conductor and forms thus an electrical connecting link between the _ 
copper conductor and a few sections of insulated rail under the car. The current | 
asses from the surface rail through the body of the electro-magnet (which is 
insulated from the body of the car) into the motor, and finally into the ordinary 
tram rails and earth in the usual manner. The electro-magnet is energised by a 
shunt current obtained from the main conductor, but to provide for the possibility 
of dropping the strip from some unforeseen cause there is placed on the electro- 
magnet a third thick wire coil, which can at all times be energised by two storage 
cells carried on the car, and thus the strip can be picked up and the main circuit 
again established if it should have been accidentally interrupted. It may, however, 
at once be stated that during some tests made on an experimental line of this 
kind, and which lasted over several days, there has been no need for the picking-up 
battery, as the current was never lost. The way in which Mr. Lineff makes use 
of magnetic lines of force to effect the attraction of the iron strip deserves 
attention. It might perhaps be thought that the most direct, and therefore 
the best, way of utilising the lines of force would be by one single line of 
sectional rail, through which there would be longitudinal magnetic flux cor- 
responding with the fore and aft position of the poles, and attraction of the strip 
at every gap between two sections. Experiment has, however, shown that this 
apparently direct way is by no means the best way, and that far more satisfactory 
results can be obtained by arranging a more roundabout course for the lines of 
force. This is attained by the employment of the subsidiary or buried rail, the 
gaps in which do not exactly correspond with those in the main or surface rail, but 
are shifted forward by a certain amount. In consequence of this arrangement the 
buried rail acts as a kind of magnetic bridge to successive portions of the surface 
rail, and this action takes place in two ways, one direct and the other indirect. 
The direct way is longitudinal and does not affect the strip at all. The indirect 
way is both longitudinal and transverse, the latter passing several times through 
the strip. The buried rail isa rather imperfect bridge to the lines of force traver- 
sing it longitudinally, because its magnetic resistance in that direction is great, but 
this rail forms a very efficient bridge for lines passing through it transversely, owing 
to its lower magnetic resistance in that direction which includes the strip. The 
