We will consider now the case of a steamship to be lighted by means of
incandescent lamps. It is sometimes a matter of some difficulty to fix
on a suitable position for the dynamo and engine, especially in ships
which have already been running for some time. In selecting a position,
it must be borne in mind that a dynamo will work best in a cool clean
place, cleanliness being most important. If a lot of coal dust is flying
about where the dynamo is working, it will be drawn into it, and tend to
impair its electrical, as well as mechanical efficiency. If the dynamo
is kept properly lubricated, it will work well enough in a hot place,
but we must remember that the heating of the wire which makes up a large
portion of the dynamo, reduces its conductivity, so that the cooler it
is kept the better. The dynamo should be so placed that the engineer can
get to every side of it easily. If a quick-speed engine is to be used
for driving it direct, it will make a very compact installation, but
there seems to be some difficulty as yet in getting suitable reliable
engines, besides which many marine engineers object to quick-speed
engines altogether. If a slow-speed engine is to be used, a belt is of
course required to get the necessary speed on the dynamo, and various
precautions are needful to prevent the belt slipping off the pulley when
the ship is rolling about in a sea-way. In all cases, the engine and
dynamo should be placed with their spindles fore-and-aft, or in a line
with the ship's keel, the rolling being felt more than the pitching.
There are various ways of keeping the belt from slipping off the pulley.
Some have flanges on the pulley, others have guides or rollers on each
side of the belt, each plan having its advantages and disadvantages; but
some plan must be used, otherwise the belt slips off, usually in the
middle of the first-saloon dinner, and out go all the lights, besides
which the belt may be considerably damaged before the engine can be
stopped. The engine must be one that will work very steadily, otherwise
the lights will pulsate at each revolution of the engine, which is most
unpleasant. If the engine is a single one, it must have a large
fly-wheel, or a driving-wheel large and heavy enough to answer the same
purpose. The engine requires a good sensitive governor, so as to keep
the speed regular when some of the lamps are turned on or off. When the
engine and dynamo are in the main engine-room, the throttle-valve, or a
stop-valve, should be in a convenient place for the engineer on watch to
get at so as to instantly shut off the steam if the belt slips off or
breaks. In ships where an electrician is carried there will not be the
same necessity for this precaution. It is necessary to have some means
of tightening up the belt, so as to keep it from slipping round the
pulley. Where the engine and dynamo are on the same level there may be a
screw arrangement in the base-plate of the latter by which the distance
between centres can be increased. Where the engine and dynamo are on
different levels, and the latter is a fixture, recourse must be had to a
roller, bearing against the upper part of the belt and capable of screw
adjustment. If link leather belting is used, it will be found necessary
to take out several rows of links each day until it has finished
stretching. A very handy thing to use for this purpose, and which can be
made on board by an engineer, is a double clamp with a screw in between,
just like the ones which are being sold for stretching trousers which
have got baggy at the knees. Whatever belt is used, it is very important
that there should be no joint or inequality which can cause a jump or
slip when going over the pulley, as this will cause the lights to
pulsate each time. In America friction gearing has been tried, but I do
not know with what success. From my experience of friction gearing, I am
inclined to think it might do very well. There is certainly no doubt
that direct-acting quick-speed engines are the ones to use, and it is
only a question of getting a suitable one.
The dynamo being firmly fixed in position, the main leads are connected
to it, and carried along to the switch-board, which should be in a
convenient position near at hand. On this switch-board are usually
placed the large safety fuses. The board should have a cover to it, to
prevent any one meddling with it, and to keep it clean. The main leads
are of a large size, and from these other smaller ones branch off, being
spliced and soldered to them. It is a very good practice to use leads of
two different colours, as we can then work by the following rule: Never
connect together two leads of different colours except by means of a
lamp or other resistance. The size of the various leads depends on the
current to be conveyed, and is a matter for the electricians. On the
main-deck of a large passenger steamer, the main leads may be carried
along side by side under the upper deck, and from these, smaller ones
branch off into the various sets of rooms, smaller ones still going into
each room. In each room there will be one lamp with its switch to turn
it on or off as desired, and a safety fuse. The lamps are held in small
brackets, and are contained when desired in frosted globes, which
diffuse the light and make it very pleasant. When these globes are held
rigidly in the brackets, the least knock breaks them. A very good
bracket I have seen in use is one which allows the globe to move about
on its support when touched, being at the same time sufficiently a
fixture to resist the motion of the ship; and in the particular ship in
which I saw these used in the first saloon, there was not a single
breakage during a four months' voyage. The switches for turning each
light on or off can be under the control of the passengers, or, on the
other hand, they can be fitted to work with keys kept by the stewards,
as thought most desirable.
The lamps used can be of various candle-powers, within certain limits,
and of whatever make is considered best. They can also be of various
makes, as long as they are constructed to stand the same E.M.F. The
lamps in the passenger berths give quite sufficient light if of
10-candle power; the ones for lighting the saloons, passages, and other
large spaces, may with advantage be of 20-candle power. In these days of
luxurious travelling, when the various lines are trying to attract
passengers to their particular ships, what follows may be thought worth
consideration. In steamers going through the tropics to India, China,
Australia, &c., it is usual to get up dances, concerts, and other
entertainments on the quarter-deck, at times when it would be impossible
to do anything below on account of the heat. The quarter-deck then has
to be lighted up. This is effected by means of globe oil-lamps hung
about here and there, two being hung in front of the piano, in
unpleasant proximity to the head of the obliging lady pianist. Now in a
ship lighted by electricity, there is no reason why a couple of leads
should not be brought up from below through a skylight or other opening,
on to the quarter-deck. Indeed the leads might be arranged to screw into
a place in the deck, or on the side of a skylight, just in the same
manner as a hose is connected for washing decks. These leads would have
holders for lamps fitted permanently at intervals, and when required for
use would be stopped up along the awning-spar or ridge-chains, and the
lamps screwed or hooked into the holders. With a few handy men, five or
ten minutes would suffice to arrange the whole thing after the leads had
once been fitted. The leads once fitted for this purpose would be
always ready for use, and could be kept coiled away in a box which might
also have a compartment to contain the dozen or so of lamps required.
If the dynamo is already running as many lamps as it is capable of, some
of the bedroom lights may be turned off while the quarter-deck is being
lighted. Another thing which I think has not yet been done is the
following. When working cargo at night, and indeed during the day to
some extent, lights are of necessity used in the holds. The _theory_ is,
that no naked lights shall be allowed, but the _practice_ is this: lamps
are taken below, get knocked about, the wicks fall down and want
pricking up, the lamps are opened for this purpose, and as they are
found to give more light without a dusty glass round them than with it,
they are left open. Candles are often taken below lighted, and even
matches struck to see the mark on a bale. I am aware that arc lamps are
used in the Royal Albert Docks, London, in connection with the dock
lighting, lamps being carried below when required, with flexible leads
attached, and that, in some few steamers, arc lamps have been used in
the same manner in connection with their own plant. These arc lamps are,
I think, not nearly as suitable as incandescent lamps for the purpose of
lighting up a ship's hold; the light is too glaring, and casts deep
shadows amongst the bales and cases, besides which, the lamps are large
and clumsy. I would suggest that leads should be carried behind the
stringer-battens in the ship's side, or along under the next upper-deck,
having simple sockets or holders for incandescent lamps at certain
intervals. Whoever might be in charge of the hold would screw or hook on
the lamps as required, and so light up every part of the hold thoroughly
while work was going on. There would be no risk of fire, and I am
convinced that the extra leads and lamps would pay for themselves in a
very short time, because work would get on more quickly, and pilfering
of the cargo would be in a great measure put a stop to. The leads for
the holds could be so arranged as to be quite unconnected with the
dynamo while at sea, so that there could not be the remotest possibility
of the current finding its way below when not wanted. In fine, there is
no reason whatever why a ship's hold should not be lighted up when
required, as well as a warehouse or store on shore.
Now, we will suppose that our installation is complete, ready for
working, everything having been pronounced in order by the electrician
who has looked after the work. Evening is approaching, and the lights
will soon be required; we must therefore see that our engine and dynamo
are ready for a start. If the engine and dynamo are separate, the belt
must be felt, to see that it is tight enough, otherwise it must be
tightened by whatever means are provided for the purpose. We must also
see that the engine and dynamo are properly oiled, and that the
worsteds are down the tubes of the oil-cups, and working properly, not
dry, as I have known them to be, with fatal results to the dynamo. If
the lubrication is performed by means of tubes leading to each bearing
from an elevated oil-box, we must see that the oil really gets to the
bearings, and regulate its flow as required. The commutators and
collector-rings and rubbers require only a wipe of oil, just sufficient
to prevent undue wearing of the surfaces; if too much is put on them,
they will spark a great deal, and sparking will wear them away more
quickly than friction. The brushes of copper wire which collect the
current of the exciter dynamo, and others of similar pattern, must be
placed so that the ends press on the commutator as shown in Fig. 21.
The ends should project just a little way beyond the point or
line of contact, and when the dynamo is running, there should be
very little sparking. I am supposing that our plant consists of an
alternating-current dynamo with a small exciter. The wires leading from
the exciter to the other dynamo remain always connected, as there is no
need for meddling with them.
[Illustration: FIG. 21.]
[Illustration: FIG. 22.]
We will now start the engine, and thereby set the dynamo going round,
slowly at first, and gradually up to the speed required. The main
switches are not yet turned on, so there is no current going through the
leads as yet; what then is being done? A current is being produced by
the exciter only, and is magnetising the electro-magnets of the larger
dynamo, and if we want to know if it is really doing its work as
intended, we just hold a small pocket-compass over the ends of two
opposite magnets of the dynamo, and observe how the needle points. It
should at once take up the position shown in Fig. 22, and if then held
over the next couple in like manner, the needle should simply turn
round, and point in exactly the opposite direction. If it points in any
other direction, there is something wrong with the connections. If,
however, the connections are right at starting, they will of course
remain right, and there should be no need for this test. It is well to
remember that when dynamos are working, they are, or contain for the
time being, very powerful magnets, therefore if we bend over them to
examine them, our watches will get magnetised, which does not improve
their qualities as time-keepers. Say that our dynamo is now going round
at the required speed, which may be 500 or 600 revolutions per minute;
the engine is not using much steam as yet, because very little work is
being done. We now switch on a set of lamps; this closes the circuit,
and the large dynamo begins to produce its alternating current, which
goes through the lamps and lights them up. This, however, gives the
engine more work to do, and more steam must be turned on, otherwise the
necessary speed will not be kept up. We switch on all the other lamps as
required, and must see that the speed of the dynamo is kept constant. A
difference of a few lamps, affecting the engine to a small extent only,
should be compensated automatically by the governor. If the brightest
lamps are not bright enough, the speed should be increased a little, but
care must be taken not to overdo it, because if the current is too
strong, some of the safety fuses will melt, and the corresponding lamps
will go out. It must not be inferred from what I have said, that it is
necessary to run the dynamo at first without switching on any lamps. On
the contrary, a better effect will be produced if all the lamps are
switched on before starting, as they will then gradually work up to
their full brilliancy; whereas, if one set of lamps is started first,
and run bright, and we then switch on another set, the current at first
will be too small for the two sets, and the first set will get quite
dull, remaining so until the dynamo is going at its proper speed again.
When lighted up for the first time, it will be found that some of the
lamps are much brighter than others; this is because the lamps at
present made are not of perfectly equal resistances. We must go round,
then, and note where the dull ones are, and we can either at once, or
during next day, shift them into the bathrooms and places where such a
perfect light is not required. All the lamps in one room, the first
saloon, or music room, for instance, should be equalised as much as
possible, and in such places the brightest should be used. Nothing looks
worse than to see a couple of dull lights in the same room as a lot of
bright ones. By seeing to these matters we can make the lighting much
more satisfactory than it otherwise would be. During the first few
evenings we shall probably have some of the lamps go out through the
filaments breaking. This I consider a weeding out of defective lamps,
because if it were that the current was too strong, the fuses would have
given way. Some of the fuses give way when the current is _not_ too
strong; this is owing to imperfections in the fuses, and they must be
replaced by spare ones. For the sake of economy, it is well not to run
the lamps too bright. Without giving the lamps the maximum current a
very good light can be obtained, and they will last all the longer. I
need hardly say that there is a medium in this as in everything else,
and it does not look well when a candle is placed alongside of an
electric lamp to enable a person to read or write in comfort.
All this time the dynamo is running, and we must feel the bearings
occasionally to see if they are keeping cool. There will be no trouble
if the lubrication is all right. If the oil does not get into the
bearings as it should do, they will heat, jam the spindle, or seize, and
bring up the engine or break the belt. The lights will then all go out,
and everybody will say hard things of the electric light, while the
fault really rests with us. Sometimes seizing occurs through the spindle
not being slack enough in the bearings, but this generally occurs while
testing the dynamo at the works.
It must be borne in mind that in dynamos the spindle must be a good fit,
and there may be room in the bearings for ordinary engine-oil while
there may not be for a thicker oil, such as castor oil. Therefore, if
the bearings show a tendency to heat, it may improve matters to thin the
oil used with petroleum. While giving the dynamo its proper supply of
oil, we must only apply it in the proper places. If we let the bobbins
get smothered in oil, the insulating material on the wire will get
rotted, and a short circuiting will probably take place. The dynamo
cannot be kept too clean, and there should be a canvas cover to put over
it while not in use, especially while coaling. We will suppose that all
is going on right; a steward comes along and says: "Mr. So-and-so, I
cannot get the lamp in number 6 berth to light although I have turned
the switch the right way." "All right, I will go and look at it," you
answer. Now, let us see what is the matter. We unhook or unscrew the
lamp, and look at the filament; it is not broken. We replace the lamp
again, and are careful that it makes good contact; but still no light.
Let us look at the safety fuse; why, there is none! it has been missed
out. We get one of the spare ones out of our electric store, and put it
in its place, and the lamp lights properly at once. We find another lamp
out, and look at it. We see at once that the filament is broken, so
there is no question about this one; it must be changed. Hallo! what is
up with this one? it goes in and out all the time like a flash light.
The current must be getting to it all right, otherwise it would not
light at all. I see what it is; it is a Swan lamp, and the spring is not
pressing quite fairly on it, so that one hook is making good contact,
while the other tightens and slacks with the vibration of the ship. This
is soon set right by turning the spring round a little, or hooking the
lamp the other way. Or it is an Edison lamp, which has got slightly
unscrewed, and no longer makes good contact at the back end of the
holder. In some lamp-fittings the ends of the leads are held in a spring
grip in the base of the bracket, and it may happen that they have
slipped out, and so broken the circuit, and extinguished the light. In
the Swan lamps, and others of a similar pattern, one of the little
platinum loops in the base of the lamps sometimes gets broken off; the
lamp is then of no further use. To recapitulate, if a lamp goes out, the
first thing is to see if the filament is broken, next if it makes good
contact. If it does not then light up, see if there is any current
getting to it; this may be found out by touching the two hooks in a Swan
holder, or the back and side of an Edison screw holder, with a moistened
finger. With a current of 50 volts a slight tickling sensation will be
felt if the current is passing through. If this cannot be felt, there
must be some part or other disconnected, perhaps the safety fuse has
given out, or the ends of the leads got adrift from the bracket. If in
any doubt about the lamp, try another in the same place.
In some steamers incandescent lamps are used in the side lamps; they can
easily be fitted for this purpose, especially when the ship is provided
with lighthouses built in, as in the Anchor Line steamers. Two or more
incandescent lamps can be arranged on a small stand, which will slide
into the lantern, taking the place of the regulation oil lamp, and
connected by flexible leads to the other leads. It would be easy to put
six 20-candle power lamps in a group in each lantern, as it does not
matter in what position they are placed; two might be used on ordinary
occasions, while on a foggy night, the whole six could be switched on.
If one lamp went out through the filament giving way, it would not
affect the others, so that there would still be a light in the lantern.
If, through some breakdown of the engine or dynamo, the electric current
were no longer to be had, then it would only be necessary to withdraw
the stand of lamps, and put in the ordinary regulation oil-lamp. The
mast-head lamp could also be fitted with the electric light, as indeed
has already been done. On no account, however, should an arc light be
used, as besides being too dazzling, it is much too uncertain; in fact
many other reasons could be given for rejecting it. It is even a
question whether it is an advantage to have incandescent lamps for a
mast-head light. There is certainly the great advantage of not having to
pull the lamp up and down to trim it, a rather risky performance in
heavy weather, and also of the light not being affected by any wind that
may get into the lamp; though as regards the first, English officers
would never be satisfied to see a lamp dangling on the stay all day
long, as appears to be the custom in some foreign steamers, besides
which it would have to be lowered to be cleaned outside.
The present mast-head lights are quite powerful enough already, too much
so when compared with the side lights. I am not aware of any collisions
having occurred through a mast-head light not being seen in time, but
how many from the side lights not being seen! It was no doubt
contemplated, as indeed the regulations show, that no lights should be
visible about a vessel, except the regulation lights; but many who have
seen a large passenger steamer go past will have noticed how her side
was--one, two, or three rows of dazzling bright lights, and will have
looked almost in vain for the green or red light dimly visible in the
midst of all the bright ones. If bright electric lights, therefore, are
shining through the ports, we must have our side lights at least as
bright, so as to give them a chance of being seen. If electric lamps are
used as side lights, the dynamo must be kept running all night. If it is
thought desirable to put out all unnecessary lights at 11 P.M., the
leads can be so arranged that these lights can be all on one or more
circuits, and the necessary ones on another.
Although the dynamo will have to go at nearly the same speed throughout
the night, it will not have the same amount of work to do, and the
engine will therefore use much less steam, the consumption being in
proportion to the number of lights used. An economical engineer will
therefore see that bedroom lamps are not kept lighted all the evening
without any necessity. On shore we should never think of keeping
gas-lights blazing away for no purpose, and why should we use
electricity with more lavishness, especially when it is so easy to turn
a light on or off. The switches might with advantage be painted with
Balmain's luminous paint, and there would then be no trouble in finding
them in the dark. It is well to know that on board ship, probably in all
cases of electric lighting, there is no danger to life to be apprehended
from touching any of the leads where bare, or indeed any part of the
dynamos, as the E.M.F. is usually not more than 50 volts. It is best,
however, not to try any experiments, and it is a good general rule, not
to touch a bare part of a dynamo or lead with both hands at the same
time. The fear of getting hurt has the good effect of keeping passengers
and others from meddling with their lamps.
I have said nothing about the use of electric lights in binnacles,
though it would be a great advantage to be able to supply them with a
good steady light quite unaffected by wind. There is an obstacle to
their use for this purpose, in that the electric current being used near
the compass, the latter is affected by it. In theory, an alternating
current should have no effect; but it would require very exhaustive
experiments to be made before enough confidence could be inspired
concerning its innocence, and I fancy it would usually be looked upon
with great suspicion by captains and officers of ships. The dynamo being
made up of powerful magnets, must of course be always at a good distance
from the compasses. In some installations on iron steamers, the return
leads have been dispensed with, the iron of the ship carrying the
current back, in the same way that the earth or sea does it in a
telegraph circuit.
It is to be observed that a dynamo with _brushes_ on the commutator is
not necessarily a _Brush_ dynamo as a good many people seem to think,
the latter being named after its inventor, Mr. Brush.
A dynamo is not a _battery_ as some people call it, and there is no need
for multiplying names.
A pocket speed-indicator should be supplied for testing the speed of the
dynamo, to see that it is kept up to proper speed, and that the belt (if
used) does not slip to an unreasonable extent.
I think I have now said enough to redeem my introductory promise, and if
I have, so to speak, let more electric light on to a subject previously
dark to a good many people, I shall be well satisfied with my labour,
and I hope that those who peruse this book will be induced to go more
deeply into the subject by means of the many good books which have been
written by cleverer men than I, and which enter more thoroughly into all
its details.
[Illustration]