1290 THE COLLIERY GUARDIAN. December 24, 1915. MANCHESTER GEOLOGICAL AND MINING SOCIETY. There was an unusually large attendance of members at the meeting of this society on Tuesday last, when the following new members wTere elected :—Members (federated) : Frederick S. W. Dobbs, Brookside Cottage, Westleigh-lane, Leigh; Thomas Bernard Morgan, The Lawns, Rainhill, Lancashire. Associates (federated) : William J. Jones, 178, Dumfries-street, Treorchy, Rhondda; Howell Jeffreys, 6, Lawn-terrace, Treforest, Glamorgan; Ernest J. Phillips, 29, Pleasant-view, Godreaman, Aberdare; Evan Bevan, 1, Lewis-street, Treforest, Glamorgan; Morris Hughes, 6, Lawn-terrace, Treforest, Glamorgan. Students (federated) : Cecil J. Davies, 6, Lawn-terrace, Treforest, Glamorgan; William Moore, The Cottage, Cwmpennar, Mountain Ash; David George Price, 17, Dunraven-terrace, Treorchy, Rhondda. The President (Mr. Leonard R. Fletcher) mentioned that, in connection with the collection among the- societies affiliated to the Institution of Mining Engi- neers for the provision of Red Cross motor ambulances, the sum of £257 has been subscribed by individual members of the Manchester Society. This was both dis- appointing and satisfactory, and, at the meeting of the council that afternoon, it had been decided, subject to the approval of the members, to make a grant of .£50 from revenue. The members expressed their approval of the proposal. The British Association : Delegate’s Report. Mr. Wm. Watts, the delegate of the society to the meetings of the British Association held in Manchester, presented his report of the proceedings, in the course of which he emphasised the importance of the views expressed by the president of the association in regard to the organisation of the various affiliated societies in arranging details of local research. The opening of museums, he said, for the interchanging of specimens and the preservation of things of interest, including plants, antiquities, and fossils, for the use of the mem- bers, was a matter calling for attention. The value of the loan and exchange of specimens for educational pur- poses could not be over-estimated, and in that respect, both from a national and local point of view, museums could be made more useful for study. By way of “ general observations,” Mr. Watts observed that no matters of scientific interest were discussed at the con- ference, which seemed to lack organisation, when one remembered that 107 societies were represented, con- sisting of more than 25,000 members in the provinces. Intercourse ought to be more generally cultivated, and the scientific work of each society formulated, so that a syllabus of the matters to be discussed could be placed in the hands of the delegates. The importance of organisation and method ought to be kept clearly before them, and there was a great deal the affiliated societies could do in connection with science in their respective districts, if properly organised. The study of local soils, bird and insect life, migration of birds, tree and plant life, rainfall statistics, changes of atmospheric tempera- ture, evaporation, denudation, and the dip, strike, and nature of the geological strata — were all subjects of scientific importance which local societies could con- veniently investigate, and thus render invaluable service to research work. Mr. Watts was thanked for his report. Visual Signalling. Mr. Harold Green then read a paper (which is given on page 1288). In the discussion which followed, The President (Mr. Leonard R. Fletcher) said it had always seemed to him that, in connection with the ques- tion of visual signalling, the Government had adopted rather a strange attitude. He supposed they wanted to stimulate invention by ordering mine owners to use something which had really not yet been invented, because at the time the regulation was made, there was not a satisfactory visual signalling apparatus on the market. He accepted most of the conclusions arrived at by Mr. Green, but he was not quite in agreement with regard to the suggestion that the visual signal should be taken off directly the engine was set in motion, because, in his opinion, it was better that it should remain before the engineman’s eyes until it was can- celled by another signal, or by the engine coming to a standstill. Another important point, to his mind, was that it was quite impossible to adopt visual signalling with success so long as they had the same signal for “go on ” as for “ stop.” He was not one who wished to interfere with signals they had been accustomed to for many years, but he did think that the Government, while arranging a code of signals to be adopted in con- nection with winding at pits, might have paid more atten- tion to the fact that, at present, the same signal was used for “ go on ” and “ stop.” He always understood that one of the objects of visual signalling was that, in the case of a dispute between the engineman at the top and the onsetter at the bottom, there might be some- thing in writing, as it were, to show who had made the mistake. At present, so far as he could see, they were no nearer to an improvement in that direction than they were before. After an accident they would still have the engineman saying he had a signal to “ go on,” and the onsetter denying that he ever gave the signal at all. If visual signalling was to be generally adopted, some- thing would have to be done in regard to those signals. It was a subject that required careful discussion, and he was sure the members would appreciate the importance of Mr. Green’s paper. Mr. Gerrard (ex-H.M. inspector of mines) said the subject was one which divided mining men more than any other subject. With regard to the signal for “ go on” and “ stop,” he thought it would not be wise to alter the present signal for “ stop,” because the emergency of stopping required the simplest possible signal. Again and again the importance of that had been brought home to mining men in connection with accidents. A vote of thanks was accorded Mr. Green for his paper; and the discussion adjourned to a future meeting. The members afterwards examined a number of visual signalling apparatus exhibited by various makers. A signal indicator invented by Mr. Green was explained by a representative of the Automatic Telephone Manu- facturing Company Limited. The instrument is arranged in a neat but substantial teak case, the signals being indicated on the front (by means of lamps) as a luminous stencil, with an opaque ground showing the number of rings, the nature of the signal from the level from which it had been given. Ten panels, arranged vertically, are provided for each level, the first five being for the recognised Home Office code, and the wording of the next four being left to be determined by the manager, whilst the last becomes luminous for every signal given, and indicates its origin : “ bank,” “ bottom,” etc. One of the points claimed for the system is that there is a definite cancellation of the signals on the slightest move- ment of the winding engine, and as the moving parts have very little inertia, the indicator will respond to extremely quick ringing; in fact, asserted the demon- strator, it was impossible to ring too quickly. In addi- tion, further signals can be given whilst the engine is in motion, and can only be cancelled when complied with. Another advantage impressed upon the audience (and this was also claimed by the supporters of other systems) was that no alterations to existing audible signals were necessary, as only one wire to each level was required, and it could be adapted to any mechanical pull bell system at present installed. The working pressure is 12 volts, and as the accumulator battery is kept auto- matically charged, the amount of attention required by the apparatus is reduced to a minimum. The Wigan signalling system is an indicator com- prising two dials and a “ men ” panel. One dial registers the signal from the banksman, and the other from the onsetter; and whenever men are about to ascend or descend, the fact is announced by means of a luminous panel. The pointers are so constructed that they remain at the last signal until a further signal is sent, or until the engineman proceeds to carry out the order, after which the pointer returns to the zero posi- tion. According to Mr. Heyes, who conducted the demonstration, the indicators are absolutely non-cumu- lative, and cannot under any circumstances add on to a previous or subsequent signal. Asked what arrange- ments were made for re-setting the pointers to zero when the engineman proceeded to comply with the order, he explained that the operation could be carried out by two methods. First, by means of special contacts attached to the winding depth indicator, which enabled the pointer to be returned to zero by the movement of the engine at any pre-determined point in the wind; and, secondly, by means of a special magneto arrangement, which enabled the pointer to be returned to the zero position at any time by a slight movement of the engine, even in so short a movement as that made in changing from one deck to another. The Scott and Wheatley automatic indicator was advocated for its simplicity of working parts,* with nothing to get out of order when attended to with ordi- nary care. The apparatus consists of a sheet steel case enclosing the mechanism, with one dial for the onsetter and one for the banksman, each fitted with a gong of different tone. All signals during operation remain visible until complied with, whereupon they are released to zero. The first signal the banksman and engineman receive, when men are ascending or descending, is 3 (indicating “ men ”), which remains while the signals “ Raise steadily ” or “ Lower steadily ” are given and complied with. In connection with this apparatus, attention was called to the seam indicator, the advan- tage of which is that, when the signal from one seam is accepted, and a signal is given from another seam, it automatically releases the former signal to zero. Another point advanced was that all signals can be released to zero, either by the person giving the signals, or by the engine itself, and can be coupled to the existing wires from onsetter and banksman. The Davis self-contained solenoid bell with dial indi- cator was also exhibited, the system consisting of a bell with two electrical solenoids, or two levers and plungers (mechanical), with an indicator which shows the nature of the signals. When signalling “ men about to ride,” the onsetter gives three signals on the “ men ” push or pull, which rings 3 on the banksman’s bell and, in the engine house, on the indicator bell marked “ onsetter,” and the word “men ” appears in an open space in the dial which is visible to the engineman. When the men are in the cage ready to be raised, the onsetter gives 1 on a second push or bell, which rings 1 on the banks- man’s bell, and, in the engine house, on the indicator marked “ onsetter,” and the pointer is carried to 1 or “ raise.” The indicator would then read “ men ” and 1 or “ raise,” which would remain visible until the signal was carried out. An indicator was also displayed by Mr. Jobling, and, in addition, attention was called to the “ Migas ” detector and a safety gear for colliery cages. ATMOSPHERIC CONDITIONS AND THE HEFNER LAMP. At a recent meeting of the National Illumination Com mittee of Great Britain it was reported that the committee had in hand the results of a study, by Dr. E. Ott, of the Zurich gas works, of the effects of atmospheric conditions upon the light given by the Hefner lamp. Dr. Ott’s report has now been translated by Mr. W. J. A. Butterfield, hon. secretary and treasurer to the British committee, and a copy of the translation is published in The Gas World, from which the following has been extracted. Dr. Ott says that Dr. E. Liebenthal, member of the Imperial Physical-Technical Institute, Charlottenburg, pro- posed the following formula for the illuminating power, y, of the Hefner lamp :— y = T049 — 0-0055a;-0-0072 (z'_ 0-75)+ 0-00011 (5-760) in which :— x = the volume, expressed in litres, which the aqueous vapour associated with 1 cubic metre of dry air free from carbon dioxide would have at the same tempera- ture and same pressure. x' = the carbon dioxide contained in the air expressed in the same manner; and b = the atmospheric pressure within the range 735 to 775 mm. of mercury. On the other hand, Mr. Butterfield, Dr. J. S. Haldane, and Mr. A. P. Trotter, found the formula :— 100 I' = — in which .-— I' = the varying light of the Hefner lamp expressed in terms of its light I in normal conditions; a = the varying percentage by volume of aqueous vapour in the air; A = the normal percentage of aqueous vapour in the air ; c = the varying percentage by volume of carbon dioxide in the air; C = the normal percentage of carbon dioxide in the air; p = the varying atmospheric pressure in mm. of mercury; P = the normal atmospheric pressure at sea-level. y = 1, and I' = I (1 Hefner unit) when the Hefner lamp is burning in normal conditions, i.e., with an atmo- spheric humidity of 8*8 litres of aqueous vapour; carbon dioxide amounting to 0*75 litre per cu. m. of pure air, and an atmospheric pressure of 760 mm. (“ Pure air,’’ in the sequel, always signifies dry air free from carbon dioxide.) (a — Ac — C _ p — P\ O+F W035 12’5 J --------------------------T 100 Curve----------« Without Correction for Carbondwide £ Aqueous Vapour With to to 9 8 76 54 3 2 1 Decrease tn the Light, per cent. » o 2Oi >6 ’0 800 90 80 70 60 50 40 30 20 17 10 700 90 80 70 60 50 40 30 ■ 20 u? 600, -i 20 ---(6 - 10 - 800 - 90 - 80 - 70 ! 60 Il 50 /- 40 - 30 - 20 Decrease in tne Light on - --|7 Reduction of the Atmospheric _ , n Pressure fr-om 916 to n 7 mm u------------0-95% -700 ----------1-107o - 90 - 80 - 70 - 60 - 50 - 40 - 30 Decrease in the Light on i Reduction of the Atmospheric j ° Pressure from 717 to 6W 5mm JAnn =<9 69% i600 ----------=5’<99% Decrease Observed in the Light of the Hefner Lamp on Reduction of the Atmospheric Pres- sure from 816 to 614 5 mm. of Mercury. Mr. Butterfield communicated the results obtained in England to the International Photometric Commission at its third Congress in Zurich in 1911. As the English formula contains a correction for the effect of carbon dioxide on the light of the Hefner lamp three times as great, and for the effect of ordinary fluctuations of atmospheric pressure a correction four times as great, as the German formula, the commission expressed a desire that the researches should be repeated. The president, Prof. Vautier, having suggested that this should be done at very different altitudes, in order, primarily, to ascertain the effect of atmospheric pressure, the work was undertaken by the Zurich gas works laboratory. Measurements were at first made on various mountains, but these laborious and tedious operations showed an improbable course of variation in the light with the differences of height, which might have been due to other causes. The recognition of this led to the employment of a com- pression chamber. This consists of an iron vessel which had been ordered for other purposes, and in which the desired repetition of the measurements was carried out between January 20 and 31 last. In contradistinction to the earlier work, these investigations were made at only three different pressures—at atmospheric pressure and at 100 mm. of mer- cury above and at w 100 mm. of mercury below atmospheric pressure, since this appeared to be sufficient to cover practical conditions, while the consequent curtailment of the experi- ments was an advantage from the standpoint of accuracy. The vessel, also, was thus not subjected to too great a pressure. The compression vessel had a length of 6-20 m. ( = 20-3 ft.) and a diameter of 1-80 m. ( = 5-9 ft.). For prac- tical reasons it was used in the upright position.