THE GEECEN “SPEEDOGRAPH ” A RECORDING SPEEDOMETER FOR THE LONG-DISTANCE MOTORIST
ALTHOUGH the 3o m.p.h. limits make driving in the neighbourhood of big towns extremely tedious, it is still possible to plan in England those long, fast journeys which are the essence of sports car motoring, and with the summer holidays in prospect, Cornwall, the Lake District and Scotland suggest themselves as venues for trips of this sort. The pleasure of these journeys can be further increased by keeping a log of times and distances accomplished, but unless the driver is accompanied by a passenger who is equally keen on making such records, entries become less and less as the distance mounts up. The ideal thing would be to have an instrument fitted to the car which would record these particulars automatically, and we have recently come across one named the ” Geecen Speedograph,” which actually does this. The ” Speedograph ” is very simple. The instrument is made up of two components, a centrifugal speedometer and a clock. The clock rotates a disc of specially prepared paper, and a stylus operated by the speedometer marks the paper according to the speed at which the vehicle is travelling at any particular time. The disc is graduated to show time and speed, and a second pointer records the number of miles run. A third one, operated by a pendulum, shows whether the vehicle is stationary or in motion, keeping auto-matic account of those stops for meals,
photography, and the odd cigarette, which make high averages over long distances so difficult to maintain.
The illustration shows a portion of a chart recorded by a 2.9-titre MercedesBenz in a 2,000 kilometre-Fahrt in Germany. In the centre is the record produced by the ” Speedograph,” while round the outside the owner has subsequently marked the various gradients and the towns en route, and also whether he was over or under the set speed, which was no less than so m.p.h., on each stage of the journey.
The up-and-down lines on the disc show the speeds attained throughout the run, the highest, just before ” 18 hours ” (6 p.m.) being 130 k.p.h. The only stop in the twelve hours was one of seven minutes, at 16-12, as can be seen by the break in the continuous line, while the distance covered is shown by the inside zig-zag line, which records 5 kilometrel in each up or down line. The chart is made of red paper covered with a chalky substance, and the stylus scrapes away the chalk and so leaves a red mark. The mechanism of the Speedograph is enclosed in a cover some six inches in diameter, or rather larger than the ordinary speedometer. The cover is split and hinged, the clock mechanism being ‘enclosed in the part that swings open. On the front is a clock face of normal type with a moving disc to show the clockwork
is going. The recording paper disc is clamped to a turntable likewise revolved by the clockwork. The speedometer portion is driven through the usual cable, and a small scale and pointer giving a direct indication of the speed is mounted at the top of the casing, while an electric contact, which can be set to light a tell-tale lamp at 30 m.p.h. is also included. The trip mileage is recorded on the paper, while
the season’s mileage is shown by the usual rotating drums driven by the speedometer cable. The standard model indicates speeds up to 70 m.p.h., and the disc records speed and distance for 24 hours. The instrument can be altered at an extra charge to cover other maximum speeds. such as 90 or
140 m.p.h., and the driving mechanism of the disc can be speeded up by the makers to record shorter periods, such as twelve, six or three hours. This gives a more open reading. The Geecen Speedograph is stocked and supplied by the Great Central Motor
Service, Ltd., 133, Marylebone Road, N.W.z., and the standard model costs gts. It is robustly built, being primarily intended for prolonged use on commercial vehicles. Apart from its usefulness to the ordinary tourist, the Speedograph also has appli
cation in the testing of racing cars and the logging of rallies and reliability trials.