SEMAPHORING.

Press, Volume L, Issue 14984, 3 June 1914, Page 10

SEMAPHORING.

A PRACTICAL DEMONSTBA/ TION.

EVIDENCE FOR WHANGA_L-___rs o

INQUEST,

(press association -nx-sGaiM.) AUCKLAND, June J. A practical demonstration of -___-- phoro signalling was rnado to-day for the information of Mr F. V. Fra_«r S.M., who is conducting the inquest __• garding the railway disaster on We_nesday last. Counsel for the *?__,«_. interested persons wero ako present. The inquest will be resumed on Jxtat, 10th. and evidence will then be gi~__ , that shortly after the accident the _ig- \ nal lever was looked in*the danger position, but that the signal was green for "all clear."' "j

Attention was given principally to the manner in which the semaphora operate, at night. There is only on. signal south of Whangamarino, aad h mas upon this that- the driver of t__ express train had to rely in approach-' iug the station. Tho length of t_» track between the centro of tho sta__» platform and the signal is 604 yardj, - and the signal is fixed at 30ft abov. the rail level on a pat 35ft from th. centre of the truck. The signal s___d," at the junction of two gradients, tor tho line rises towards the signal ___;'- ---curves into a descending gradient towards the station. In tho po_.ioa (.■elected for it tho signal is visible fro» the preceding mile of track. The actual length of the wire <-j_nexion between the lever and signal' including short pieces of chain passe. I round grooved pulleys to change th. direction of tho wire, is about tea j yards greater, so that the connexion j is formed by about Gl4 yards of steal I wire, .oven-eighth* of an inch in <ar»' 4 cumference. The direct distance froa, the signal level to the points switch At which tho tablet porter, William Don« aldson, was engaged when the disaster occurred, is nearly 56ft. The 6er___ ; phoro signal cons.-ts of an arm or*'blade which is pulled down or "off" tft - indicate that tho train may pass, 4ri_ in the horizontal cr "on" position hV dicating "stop." -"*•- Fixed to tho runner end of tho bl_ct_ ~ is a frame, <ontaining red and green" glasses, which moves with the blade" before a lamp, so that at night rod-if-' shown for "clangor" and green for "go ahead" or "all clear." Tho fran» holding coloured glasses is, roughly, kidney-shaped, and tho device is know*. as the "spectacle." Though the inter>. • vol' between the glasses is "only a nar"'row strip of metal'forming; part of __$ - frame, a partial movement of tho soma, - phoro will give the fulUgreen signal' which, in darkness, obscuring tho indication of the semaphore, would appear exactly the same as if the signal ha_ been moved. The maximum distance - experiment has shown that the'drawrequired at the lever to depress fully - the semaphore of .tho Whangiimariiio' signal is eleven inches, hut this chaw is only seven inches at the toot of the post. Experiment.; mado at Tester-. day's demonstration showed that a ' draw of only three inches moved tha ■ ''spectacle" enough to show tho full • green. " *

The rod or green signnl is not visible to the officer operating tho signal. His only guide.to xho position of the signal is a small' white light shining through the back of tho lamp Part of tho ap- : p&i'ttus is an iron shutter, wuich, nwv- * ihg'iritli the "sppctucie, ' ob_cure_ thiaj'. wJiito light. The Jattei is visible only" when the semaphore is horizontal," awl the signal showing full • red. A rety slight movement of tho central axis "moves the" shutter sufficiently to W- ; scure the white light completely, and when the signal is being pulled "off 71 at • night- the white light disappears Jong - before the green shows from the other * side. -'•.

There is a well-known rulo that-thi absence of a signal where a signal iaordinarily shown must be treated as a : danger, signal, and where a signalman r cannbt perceive the white light of a 1 signal which should be at danger, i. becomes his duty to ascertain whether ■ the lamp.is extinguished or the-signal . out of order. - The obscuring of the white light bya fractional movement of the signan~> designed as a guard against an lnf- '! proper display of tlie "all clear" signal,-„ and" is complete long before the full srreen shows

Thero is an electrical device known; as a "repeater," which is employed-ia"! connexion with signals that are beyond.!.-, tho range of the signalman's vision. Its:.' indicators change from "danger" to,

"clear" only when the semaphore has been completely depressed, and' th_ * "danger" indicator is restored by tlie least upward. : movement of tho" arm.''. This device was not in use at Whangsmarino. '