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THE HONGKONG GOVERNMENT GAZETTE, 15TH MAY, 1886.
facing each
which the assistant sits, when comparing the clocks, setting the mean-time clock, noting the sig hays, commutators etc., stands between them as well as a tab returned from the time-ball etc.
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The rates of the clocks are adjusted by removing or adding flat horse-shoe shaped brass we on a small shelf on the pendulums. Ten grains make a change of about a second a day in the This is of course not done to the standard clock, except when it stops, but the rate of the mead clock must be often altered and the wooden cases supplied by DENT & Co., although affording f good protection to the clockwork, have shown themselves to be at any rate not less inconvenient tropical climate, than they are known to be at home. ferable, so much more as they would allow the interior to be at all times visible. They would Glass cases with cast-iron frames would be pi course be more expensive but would also be more durable. A glass of carbonate of potash is kept the clock-case to absorb moisture.
The reversing commutator, through which the mean-time clock closes a local circuit consists on polarized relay mounted on a base board and having two galvanometers on either side.
This polarised relay consists of a soft iron magnet mounted on pivots inside a hollow bobbi, wrapped with insulated wire, and having soft iron projecting arms which work between the poles f permanent magnets. A contact lever is attached to the pivoted soft iron magnet and plays betwe two insulated contact screws capable of adjustment, and it is so adjusted that the contact lever is hel by magnetic attraction against one of the contact screws (which we will call No. 1), when no curret is flowing through the insulated wire of the reversing commutator.
The local circuit, which is closed by the hands of the clock pressing the contant springs, include a battery of one Léclanché cell, the left hand galvanometer and the insulated wire of the reversin commutator. Two other sets of batteries, of twelve cells each, are also employed,-one set for lockin and the other for discharging the electric lock of the time-ball. The negative pole of the locking battery is connected to the insulated contact screw No. 1 in the reversing commutator, and the positiv pole of the discharging battery is connected to contact screw No. 2 of the reversing commutatof The other poles of these batteries are connected to the earth.
The time-wire, through which the signal is sent is connected through the right hand galvanometr to the contact lever of the reversing commutator, and excepting during the time the local circuit closed by the clock, it is in electrical contact with No. 1 contact screw, that is from a quarter to, til five minutes past 1 p., for at other times the time-wire is disconnected from the relay and put direct t earth so as to avoid danger from lightning. This is so much more important as the line is not lail underground nor efficiently guarded by "lightning-protectors," as suggested by Colonel PALMER in 1881.
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Facing the galvanometers on either side of the reversing commutator, are contact keys. Depressing the left one closes the local circuit (in the same way as the clock does every hour) and shows the cor- dition of the local battery and whether the reversing commutator is acting properly. Depressing the right-hand key connects the time wire to earth, shows the condition of the locking and discharging batteries and the observatory-connections, and when the time-wire is connected through the galva nometer to the locking battery, any defect of insulation (from the line and earth wires touching each other or other causes) is shown by a deflection of the needle. Furthermore, every part of the electrib apparatus is tested by setting the lock about 12 h. 49 m. 40s. p. without winding up the ball and discharging at 12 h. 50 m. Os. by aid of the left key. This signal also informs the assistant in the ball-tower concerning the error of his watch, which he requires to know in order to hoist the ball at sprin the proper time. The local circuit is completely tested by observing the deflection of the galvanometer hand at some hour before 1 p. It would be an advantage to let the clock discharge the lock at some sensiti hour before 1 p. but this cannot be done as no assistant is in the tower to set the lock before a quarter s
to one.
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resti egativ
of the time-ball, there would be no difficulty in dropping any number of time-balls along the coast, it iron Although at present the time-service is, as far as the public is concerned, confined to the dropping king giving hourly signals in the Harbour Office, principal clock makers shops, banks and other public the loc worked from observatories in large towns in the United Kingdom, a separate clock of a somewhat As ex current relay, but in order to drive sympathetic clocks in buildings in Hongkong similar to those the cloc
buildings. If a cable were available, this could be effected by aid of the mean-time clock and the three, there
different but not very refined construction would be required.
the typhoon gun, pointed towards the city opposite, is placed. In the police boat-basin, at a
of the r
shorter, the l
front of the new police-station beside the mast for hoisting meteorological signals, at the foot of which. 40s. he The time-ball tower is erected on Tsim-sha-tsui Point directly facing the shipping. It stands into the distance NW of the tower, the small tidal observatory is built. The time-ball tower is about half When the mile distant from the observatory, with which it is, as already explained, connected by wire,--a sepa hand, rate wire, for exchanging messages on the A, B, C, system, connecting the observatory with the policeped gro
station.
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has two stories, and the roof of the upper story is hemi-spherical. The top of the tower is about 6 crease in The base of the tower is about 40 feet above sea level and forms a circle of 20 feet diameter. fear. Fro
feet and the top of the mast projecting through the roof about 84 feet above sea level.
On the grouner situated
floor is a massive granite pier, that supports the entire apparatus. On a copper plate (connected by through i conductor with an earthplate in the ground outside) rests the cast iron pneumatic-cylinder of 10 inch cations ent
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