FILMING LONDON BY MOBILE GENERATORS.
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Photographing by Night. The Equipment Employed. Results Obtained. Some Interesting Details of the Vehicles and Fittings.
I N our issue for last week we drew at"tention to the interest Which was being aroused all over the country by the taking of cinematograph. pictures by night of London's well-known monuments and places of historical interest, and other pictures showing phases of London's night life. The originators of the scheme, as we mentioned, were Patisi Freres, Ltd., and for their work they utilized a special lighting equipment made by Duncan Watson and Co., 62, Berners Street, London, W. Actually, two lorries mounted with generating sets, two furtherlorries, each carrying three sunlight arc protectors, a 14 seater motor coach, and a lightvan for spare parts, etc., were utilized for the work_
One of the generating sets was obtained on loan from the Famous Players Lasky Co., to islioni it had been previously supplied by the makers. The other sot, which was somewhat smaller, was hired direct from the makers.
We propose, later in the article, to deal more fully with this equipment, but we will first describe some of the work accomplished.
The vehicles left Wardour Street late in the evening and commenced operations in Piccadilly Circus at 10.45 p.m. Permission hact already been obtained from the police, and. they helped in every possible way to make the experiment a success. After this the vehicle proceeded to Leicester Square and took photographs here, and then of the Cenotaph in Whitehall, Cleopatra's Needle, the Houses of Parliament, St. Paul's Cathedral, and various other subjects, returning home at 6.45 a.m.
The results proved highly satisfactory, and some wonderful silhouette effects were obtained. Taken as they were at night time, the various statues, etc., stood out in brilliant white against the blackness of the background.
For sortie of -the photographs sunlight arcs of a total strength of 8,000,000 op. were employed, each arc developing approximately 1,400,000 c.p. The total amperage available was 1,200.
Apart from this work, the same mobile outfits are utilized for filming the interiors of buildings, etc. for instance, they were recently utilized for filming a dance at the Criterion Restaurant and other functions at the Tuscan Restaurant, and a similar mobile outfit was used by Pattie Freres in America, where they filmed the Disarmament delegates at a sitting.
The Generating Equipment.
-We obtained sonic interesting particulars of the mobile equipment from Mr. M. Pulver A.M.I.E.E. of Duncan
Watson and Pulver, the makers of the plant. The scheme emanated from America, where the largest mobile set employed was fitted -with a 60 h.p. engine. The company received an order for an equipment of this size from the Famous Players Lasky Co., but when they were about to execute it they were stopped, news having been received of a 150 h.p. set which was being utilized at Los Angeles. The engineers were therefore asked if they could fit out a similar set, the film company providing a 4-5 ton Locomobileslorry for the purpose. On this was mounted a 150 h.p. Ricardo Tank engine driving, througlr a flexible coupling, to a 72 kilowatt, 110 volt dynamo, which can easily give 700 amps. The Ricardo radiator was fitted at the front end of the lorry next to the driver's cab, and this was provided with a sliding shutter so that the air necessary for cooling could be obtained. As it was intended to run the set for many hours at a time special attention was paid to the Goofing, and the fart used. was a six-bladed Blackman, running at two-thirds engine speed.
This vehicle proved so satisfactory that a second machine was built. This time a Swiss Berna chassis was utilized, and the only difference was the provision of a larger radiator and a modified switchboard_ Incidentally, the switchboards employed are constructed of steel and bushed with mica, as slate, which is usually employed for such work, will not stand the vibration. Also the makers had to consider the question of weight, and it was found extremely difficult to keep this inside the permissible load of 4 tons. The second machine was also supplied to the Lasky Co.. in this instance for use in India.
The third machine was also a Swiss Berns, but in this case a Crossley Tank engine was employed; the spare parts for this, however, are interchangeable with those on the other engines. It is interesting to note that this machine was built for the Lubitsch Film Co., of Berlin.
Up to this point the main arrangements of the engine, radiator, etc., had followed that of the first vehicle,: but in the fourth mobile unit, the radiator was positioned at the rear and the dynamo at the front. This eliminated the necessity for removing a portion of the driver's cab, as a free flow of air could be obtained merely by dropping the tail
board. In this case a 100 h.p. tank engine was employed, combined with a 55 kilowatt dynamo. This equipment is used for hiring out to anybody requiring the use of an outfit of this description.
The large sets will supply current for four sunlight arcs, but the No. 4 set is utilized for three only, which usually prove adequate. The filth and latest outfit is still under construction, and will be ready in a few days. This is mounted on a new 5 ton Thornycroft lorry, and is being built for International Film Artists, Ltd.
There are several very interesting points about these vehicles. For instance, each is fitted with a field telephone and 300 yds, of flexible connection. These telephones have loud army buzzers, and signals are arranged so that if the engineer in charge of the generating set cannot hear vocal instructions these can be given by the buzzers.
Starting the Engines.
ft will be realized that it, is of the greatest importance that the engines of the generating sets should be capable of being started up with the utmost expedition. To assist this, the larger engines have dual magnetos and special starting magnetos, whilst the smaller machine has an ordinary magneto and auxiliary Remy ignition. 1"hree of the engines are provided with six volt Bijur electric starters, which hail from America, whilst the other two are equipped with C.A.V. starters of the Z.A.R. type, which, incidentally, is the largest eof this make tonstructed by the company. lie connection with these starters two B12 110 ampere-hour chloride accumulators, connected in parallel, are utilized, and these are charged from a specially large dynamo driven by the engine of the vehicle, and not by the engine of the generating set. In very cold weather ether is employed to enrich the starting mixture, and great care must be paid to the starting portion of the equipment, as it is quite impossible to crank these large engines by hand. The large engines are provided with two Zenith carburetters, and the small engine with one. Autovacs are used on all, and the necessary fuel for the Tank engine is drawn from the petrol tank of each vehicle.
Cooling Difficulties.
One of the difficulties experienced when the generating sets were used continuously for many hours was in the cooling, and to overcome this trouble each is fitted with an auxiliary Albany water pump driven by a belt from a pulley on the crankshaft. This pump forces water through the bottom of the radiator and excess water is returned from the top.
When in use for long periods a tarpaulin is fitted into one of tho large packing cases, used for holding the etc lamps, are filled with water, and sufficient hose pipe for connecting the Albany pump with this is carried on a reel at the back of the machine. The use of this simple arrangement does away with the need for carrying an auxiliary tank, which would have to be of considerable size.
Recently one of the generating seta was run full out, i.e., at 1,000 r.p.m., from 7 p.m. one night until 4.30 a.m. the next day. Incidentally, whilst running the rear of the chassis is supported on two 10 ton jacks, which assist in reducing vibration. When travelling the vehicle bodies are • completely enclosed by tarpaulin covers, but these are thrown back when the generating sets are running. A special rubber buffer coupling, fitted into the flywheel, is employed between each engine and its dynamo.
Switchboard Modifications.
In the smaller models the switchboards are mounted at the rear of the vehicle, but in the latest types they are mounted over the dynamos at the front end, being set askew in order to allow for operation and control by one man. For the sake of simplification and to, reduce weight the switchboards are kept down to the
• minimum consisting merely of an ammeter, vciltmeter, lamp plugs and overload automatic contact breaker.
A Pyrene fire extinguisher is conveniently carried on every vehicle.
The current. from the dynamos is conveyed by special concentric cables which obviate the need for twin leads. This cable is carried on a second reel at the rear of the vehicle. The dynamos used on vehicles Nos. 1 and 4 were supplied • by. the Electric Construction Co., Ltd., whilst those on vehicles Nos. 2, 3, and 5 were built by the Submersible Motor Co. Ltd.
Tile size of the sunlight arcs is somewhat surprising to the uninitiated. Their ordinary height is 11 ft. 6 ins., and they extend to 16 it Each weighs 7 cwt.