SOME RECENT ENGINEERING EXPERIENCES. 975 
One of the difficulties which we have lately solved is the ren- 
dering of the Port Adelaide River safer for navigation by ocean 
steamers both by day and night. The distance of Port Adelaide 
from the sea is about 9 miles, the depth of water being 23 feet 
at low-water, the width of the dredging 250 feet. The old marks 
were a series of buoys showing the channel by day and kerosene 
oil lamps at long intervals for use at night. Recent experience 
showed that this system of marking was unsatisfactory. All the 
buoys have been removed and a series of straight lines have been 
charted, in continuation of each of which is a triangular leading 
beacon, and at some distance off on the same line is an advance 
beacon, an inverted triangle; when the two are seen in line the 
vessel is on the right course. For use at night, each leading 
beacon is electrically illuminated with a white light, while the 
advance beacons are similarly lighted in red. So far as Iam 
informed such a series of electrically-lighted beacons for navi- 
gation purposes in an important water-way is new in Australian 
waters ; therefore, I have thought that a short description thereof 
would not be uninteresting. 
Highteen lamps in all had to be lit, the one at the extreme end 
of the circuit being 8? miles away from the source of current 
supply. The first portion of the circuit consists of an overhead 
wire with short leads of submarine cable connecting it with the 
beacons in the river en route. Owing to the contour of the fore- 
shore, the latter portion of the circuit consists of a submarine 
cable only, carried direct from beacon to beacon. As power is 
only available in the day time, it was necessary to make use 
of a storage battery for lighting at night, the switching “on” 
and “off” of the lights being “performed by the night watch- 
man. 
The generating plant consists of a nominal 8 horse-power ver- 
tical engine running at 180 revolutions per minute, belted to a 
shunt-wound dynamo running at 800 revolutions and having an 
output of 130 amperes at 60 volts ; and as 96 accumulators are 
used in series for lighting, it was necessary to divide the storage 
plant into four sets of 24 cells each, to be charged in parallel. 
This is done by a special commutator on the switch-board, a single 
movement of which places the cells either in parallel for charging 
purposes or in series for lighting the lamps. For charging pur- 
poses each set of cells is provided with a separate ammeter together 
with a set of carbon resistances so that the charging rate may be 
kept uniform in each set. It is, however, rarely necessary to use 
these regulating resistances, as the cells vary but little in their 
charging rate. A single voltmeter is used which is connected 
to any set by switches as desired. <A polarised cell-coupler is 
used with magnetic cut-outs on each main from the charging 
machines. Charging is carried out on every morning except 
