18^5.] 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



255 



The practical applications of Geology form another and somewhat different 

 class of investigations. They, so far as they result immediately from geolo- 

 gical principles, otter the strongest testimony to the truth of geological con- 

 elusions. Practical men assume the correctness of these conclusions, and act 

 upon them ; and in proportion as they are tried hy this test, and found to 

 succeed, the confidence felt hy the miner, the engineer, and the architect, 

 will be ditfiised generally in society, and Geology become a part of the ne- 

 cessary information required from those entering on such professions. With 

 regard to this, I would only remind you, that, to arrive at any of these prac- 

 tical results, and to draw conclusions safely, clear and definite notions of the 

 fundamentid principles, anil the methods of Geology, must be attained ; for 

 without these, however you may be able to exhibit superficial Vnowledge, 

 you cannot possibly be trusted to maV:e an observation, or draw a conclusion. 



It is sometimes, and indeed not unfrequently said, that there is hardly 

 enough yet known in Geology to justify these assumptions of importance ; 

 and that its systems and arrangements, and conclusions, are constantly 

 changing, so that what is learnt today will have to be unlearnt to-iiiorrow. 

 This, however, is the statement of persons who do not know the subject. It 

 is not true, either in fact or in inference. The foundations of Geology are 

 lound and firm, and cannot he disturbed — they are based on a rock, and they 

 may safely defy the storm of ignorance and prejudice. As fact after fact is 

 made known and added to the great store of accumulated knowledge, each 

 now finds its appointed place; the corner stones are set in, the walls are 

 rising rapidly around us, and the temple of our science already shows its 

 broad front, its noble proportions, and something even of its finished beauty. 

 It is true, indeed, that the structure is yet incomplete : here a tower is want- 

 ing to strengthen and unite into a solid mass one portion of the edifice — 

 there we may conclude, that another portion has still to he commenced ; 

 but what is done is done well. It is work that will endure, for it is based 

 on unchangeable truth. 



*^;:- 



ON THE CONSTRUCTION AND nEGULATION OF CLOCKS FOR 



RAILWAY STATIONS. 



By B. L. VuLLiAMY, Assoc. Inst. C.E. 



The fact of all the Mails in Great Britain being regulated, by order of the 

 General Post-office, by Greenwich mean time, causes the accurate perform- 

 ance of the clocks at the different railway stations to be a matter of more 

 importance than it would otherwise appear, and offers a sufficient reason for 

 in inquiry as to the sort of clocks best adapted for the purpose, and which 

 can be procured at such a reasonable cost as might be afforded for all much 

 frequented stations. 



Great practical inconvenience results from the difference between what is 

 commonly called London time and the correct mean time at the different 

 railway stations on the line. It should be noticed that the term " London 

 time" is not strictly correct, because most of the public clocks in London are 

 intended to be kept to Greenwich mean time. According to the trigonome- 

 trical survey, St. Paul's Cathedral, the most important building near the 

 Post-office, is slow of Greenwich time 23'1 seconds ; but in this paper Green- 

 wich time will always be referred to as " London time.'' 



By a certain class of individuals the variations due to the diflference of 

 longitude of a place is perfectly well understood ; but a large proportion of 

 the travellers by railway, possess only vague notions on the subject, and 

 many disappointments ensue from their arriving too late, in consequence of 

 their not understanding that their own clocks show one time while the trains 

 work by another. Fur example, take the difll'erence between Greenwich and 

 Devonport Block-house flag-staff, which according to the trigonometrical 

 •urvey is 16 minutes 39'8 seconds (to avoid fractions of seconds say IC mi- 

 nutes 40 seconds) slow ; consequently when it is 12 o'clock at Devonport 

 it is 16 minutes 40 seconds past 12 o'clock in London. Now, supposing a 

 train to leave London at 8 o'clock, a.m., and to arrive at Devonport at 2 

 o'clock, P.M., performing the distance in 6 hours. A train to arrive in Lon- 

 don at 2 o'clok, P.M., must leave Devonport at 16 minutes 40 seconds before 

 8 o'clock hy Devonport time, or the speed must be sufficiently increased to 

 cause the train to accomplish the distance in 5 hours 43 minutes and 20 

 •econds. This unavoiilable inconvenience is increased by the circumstance 

 that the difference is never the same at two cousecutive stations, but varies 

 couitautly, unless it be in the case of a train on thfe meridian of Greenwich. 



Method ofthomng London and local time «n the tame clock. 

 It appears, therefore, evident that the difficulty just noticed would be in a 

 great degree obviated, if all railway clocks were made to show both Green- 

 wich mean time, or London time, and the actual mean time at the station 

 where the clock is placed. The difference being always the same at the same 

 place, this coidd be dene without any difficulty, and at very little expense, 

 merely by applying two minute hanils to the clock, one pointing to (ircen- 

 wich mean time, the other showing the time of the place where the clock is 

 situated. Greenwich time should lie indicated by a gilt hand forming the 

 words ZiONOON TIMB, and the other minute baud and the hour hand 

 would b« mad* of tteel ai usual. 



According as the station is east or west of Greenwich, the gilt hand must 

 be placed before or after the steel hand. 



I , Upon this plan, in the case of a clock at 



the Devonport station, the two hands 

 would be 16 minutes 40 seconds apart ; 

 and when the steel bands showed 60 ou 

 the dial, the gilt hand would show 16 

 minutes 40 seconds past the hour ; in 

 like manner, when the gilt band showed 

 60 minutes the steel hand would show 

 43 minutes 20 seconds, or wanting 16 

 minutes 40 seconds of the hour. By 

 this contrivance the public would imm«- 

 diately understand that the train which 

 was stated in the railway hill to leave 

 at any given hour, really left 16minute« 

 40 seconds before that time, as showa 

 by the clocks at the place ; the time an- 

 nounced in the printed bill, referring 

 to London, and not to Devonport time. 

 On the other band, suiqiose a country 

 town, Canterbury for example, east of 

 Greenwich. The Cathedral, as shown 

 in the trigonometrical survey, is fast of 

 Greenwich 4 minutes 19 seconds, so in 

 this case the reverse would take place, and the train would take its depar- 

 ture 4 minutes 19 seconds after the time shown by the Canterbury clocks. 



.•VII railway clocks should be furnished with a seconds hand, which hand 

 should he set to agree with that which shows Greenwich mean time. Thii 

 is an additional reason for employing a seconds pendulum. 



When clocks are required to be kept to a particular time, fast or slow of 

 Greenwich, which is frequently the case, and that in setting the clock a dif- 

 ference is to he allowed ; there is always some risk of a mistake being made, 

 which is much increased by the very short time that in many cases can be 

 allowed for winding it and, if necessary, setting the clock, and more atten- 

 tion is required than can reasonably be expected from an ordinary clock 

 winder. With the double minuie hand a mistake of this sort cannot occur; 

 moreover the two hands would afford great facilities for comparing, setting, 

 and regulating the clocks by a chronometer set to Greenwich mean time ; 

 for this reason the seconds band is indispensable. 



Electric clocks for Railways. 

 Mr. Whishaw was of opinion, that the plan of marking different times on 

 the same dial would create confusion, and that it would be better that Green- 

 wich mean time should be adapted for ordinary purposes throughout the 

 kingdom. 



Four years ago he proposed, that by means of the electric telegraph, all 

 the clocks along the line of a railway should be regulated to similar time, and 

 it was to be hoped that now the electrical communication was complete 

 between London and Gosport the plan would be adopted. 



Mr. HoRNE thought the subject of considerable importance to the public 

 and to the railway companies. If one uniform rate of time keeping was 

 adopted on railways, it would tend greatly to diminish the risk of colli- 

 sion of trains. He hoped, therefore, that the suggestions of the paper would 

 be attended to. 



lie had paid much attention to the manufacture of turret and other clocks, 

 and in suspending clocks, he found the simplest method to be by pas- 

 sing a stout bolt through the hack of tbe case, traversing the wall against 

 which the clock was to be suspended, and screwing it up with a nut on the 

 outside ; the case could thus he adjusted with great exactness, and beingiso- 

 lated from tbe wall and from tbe floor was not subjecteil to any vibration. 



The paper recommended occasionally oiling the pallets. Now Mr. Home 

 always found that however small a quantity of oil was applied, tbe rate of 

 going of the clock was altered. He would rather recommend that railway 

 clocks should be placed under the care of a competent person, who should 

 wind them regularly, examine and correct their rate of going, and at the 

 same time clean the pallets, so that they would rarely require oiling. 



Mr. VuLLiAMY was quite aware that oiling tbe pallets altered, for a time, 

 the rate of going ; but he found, practically, that unless unusual care were 

 taken to clean tbe pallets occasionally, so much dust accumulated upon them 

 that a certain amount of abrasion ensued, and that a greater variation of 

 time was occasioned than could arise from oiling them, lie had frequently 

 tried the method of suspension from a single point, and approved of it, but 

 it was not always practicable, and it was more expensive than the system b* 

 bad proposed. 



Adoption of Greenwich time throuyhout the Kingdom. 

 Mr. Walker said, that be entirely agreed with Mr. Vulliamy in proposing 

 that the clocks at railway stations, in all parts of the kingdom, should keep 

 Greenwich mean time; but be thought, that Mr. Vulliamy did not go far 

 enough, for it appeared to him that a misunderstanding might still arise 

 particularly to strangers, who would be unacquainted with tbe difll'erence 

 between the clocks in the town and those at the railway stations. This 

 would be entirely removed, by all the pulilic clocks in tbe kingdom being 

 made to keep Greenwich mean time. He had recommended this measure in 

 I a report on tbi Cummuuieatiuu viith liclaud, made to the Government ia 



