From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Guide on how to test and compare the illuminating power of vehicle lamps using a candle and specific measurements.
| Identifier | ExFiles\Box 61a\1\ scan0033 | |
| Date | 2nd March 1915 | |
| R.R. 235A (150 H) (S.A. 301. 19-2-15) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 6950. 2nd March, 1915. 115 The Motor HOW TO TEST POWER OF LAMPS.—Contd. on a dark background. The lamp should be care-fully manœuvred into such a position that its light has an effect equal to that of the candle. This is the case when the circular mark is almost invisible from either side of the screen. When this condition is arrived at, we are in a position by simple measure-ment and calculation to define the candle-power of the lamp. If we describe the distance from the lamp to the screen as b, and the distance from the candle to the screen as a, this, as before, b²/a² so that for the lamp to be of the specified power its distance from the screen must be 14⅛ ins., that of the candle being 10 ins. It is probable that this experiment will also be interesting to the country reader who has not, as a rule, occasion to drive within the area to which these regulations apply, as he can thereby ascertain the lighting value of his lamps, and can on occasion decide, when contemplating the purchase of new ones, which particular lamp is more likely to be suit-able. Another point in regard to this is that very fre-quently, and especially is this the case with acety-lene lamps, the burner is not correctly placed in re-lation to the lens and the mirror. By a little adjust-ment, it is possible sometimes considerably to in-crease the lighting capabilities of any particular lamp, and by utilizing the methods just described the best position can readily be determined. These experiments may be modified if so desired, and one lamp tested against another. In such a case, one lamp will take the place of the candle, and under these circumstances the ratio, b²/a², as given for the experiment with the candle, will give the relative lighting power of the two lamps. The lamp which is farthest from the screen, of course, is the one which gives the better illumination. This would be of par-ticular interest if it were desired to compare a new lamp with an old one, with which a user was particu-larly well acquainted. [Image Caption 1] The Peugeot 12 h.p. engine. Note the accessible positions of the lighting dynamo and magneto. The adjustment at the base of the steering column is also evident. The flywheel serves as the outer member of the leather cone clutch, a fabric-faced cone being used, there being no end-thrust whatever when the clutch is engaged. It is withdrawn by a neat toggle gear, and an efficient clutch brake permits of very easy gear changing. The effect of racing on touring car design is shown by the suspension of the gearbox. The makers first intended to suspend the gearbox from four points, but when they found the wonderful results obtained from three-point suspension on their big racers, they decided to adopt it on the new "twelve." Four speeds and a reverse are provided, and the operating lever is carried on an arm projecting from the gear-box, thus frame flexure can produce no evil effects whatever, particularly as a flexible joint is incor-porated between the clutch and gearbox. The gearshafts are particularly short and stiff and are... In these times of considerable uncertainty exists as to the possibility of obtaining delivery of French cars, but in regards this model Peugeot we are pleased to point out that immediate delivery can be obtained of the chassis, and a complete touring car may be had in one month's time. Work is proceeding apace at the Peugeot works on the manufacture of touring cars, and as the engine dimensions are not those being standardized by the French Government for military work, they are immune from impressment. The new chassis, which constitutes a notable addition to modern motor engineering, may be inspected at the showrooms of Peugeot (England), Ltd., 1, Brompton Road, London, S.W. [Image Caption 2] The distinctive shape of the Peugeot frame is apparent from this illustration. The length of the springs is noticeable. The accumulator box for the lighting set is permanently mounted on the off-side frame member. | ||