1929-10-12 — Page 4

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NEXT SAILINGS.

£75.0.0. £83.0.0.

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From Hong Kong.

M.V. "ROMOLO"

·S.S.. “VENEZIA”

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SECTION.

degree from the East and West post- tion causes a large change in the· value of the generated e.m.f. when using bars each about 10 inches long, This

makes the mechanist an exceedingly sensitive detector of the null position of East and West. In fact such sensitivity is excessivo for practical use, This scheme does not eliminate the com- | matator but I'does aliminato conimuta-

MAGNETO ČOMPASS back to the same relative position with for troubles due to its very small dia- respect to the plane to the new cours the voltage to be commutated is several moter and low peripheral speed. Also If the brushes are once set in positimes as much as that of the old type tion with respect to the azimuth ring of earth inductor compas and the fit of the brushes changes run of three weeks, twenty-four hours then the actual position of contact

DISADVANTAGES OF CONVEN- TIONAL TYPE

The

commutator.

A trial

The agroto compass was described changes and considerable error is in a day, was made on the laboratory by Mr. F. P. Wills of the Marine and treduped into the operation of the com- bench to determine if wear or high re- Aircraft Engineering Department of Criticism has been offered to thesistance spots occurred and developed No cleaning or earth inductor compass because of the the General Electric Company, at the fact that there are two positions on olling of the commutator took place Aeronautic Meeting of the Society of the cammutator where zero voltage is during this time, as yet at the end of Automotive Engineers at Detroit in

generated. The positions are 180 do the run no wear was apparent on thei recent lecture. Mr. Wills pointed out green apart. It might be supposed commutator and no high resistance con- that the old conventions: type of earth that if the aviator were flying abso- tacts had developed. The pole-places inductor compan is subject to various futely blind he would not know, from of this compass are changed in azi. disadvantages which mitigate scelously looking at the azimuth ring, whether math instead of shifting the brushes; against its employment reliable,

24

was travelling in

this is a much more sensitive way of) the indicated remote indicating compass. The mag direction or 180 degrees in exactly the the point at which the flux reverses detecting the magnetic meridian and neto compass is a very considerable ad- opposite direction, 3. his indicator

The chief difference reads zero in both directions. vance in the art,

the permalloy bars. How-through

Tha between the earth inductor compass ever, if he is on the indicated course brushes are so placed with respect to and the magneto compass is that the aul not on the course 180 degrees the paie-pieces that when there is a former employs no magnetic substance therefrom, he has a very definite Inux in the bars maximum voltage in of any kind, but relies entirely on adication that such is the case. If he of voltage generated) is not materially generated. The sensitivity (or amount large armature coil of many sands of turns of fine wire connected to the right the indicator tr; reduced when the brushes are shifted a ten or twenty degrees from this maxi- a conventional type of commate yelling in the oposite direction

turns right, the indicator turns left.

The accuracy of thei tor, whereas the imaguete compara em The explanation of this is quite simplem position. ploys an alloy of nickel iron called to anyone familiar with direct current brush position-only by the position of course held is not affected at all by permalloy,

possesses certain generators, A 180 degree shift of the bars and pole-pieces. In the old very unusual magnetic characteris-brushes could be effected simply by type of earth inductor

versing the connection to them. For deviation to the right of the plane, the current flows through the indicater in the epposite direction, giving the reverse indication.

Sails on or about 29th October.' Sails on or about 7th November.

to

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M.V.. "ESQUILINO"

8.3. "ROSANDRA”

M.V.ROMOLO"

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From Hong Kong.

- Sails on or about 15th October.

Sails on or about 2nd November. Sails on or about 30th November.

OF STEAMERS

FROM CALCUTTA & COLOMBO TO SOUTH AFRICAN PORTS.

S.S. UMZUMBÍ"

Salls from Calcutta 3rd Nov. Regular Passeriger and Cargo Service to South African Ports. Through Bills of Lading issued from Hong Kong.

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NYUSUNE

REDUCED THROUGH TICKETS TO EUROPE VIA U.S.A. VARYING FROM £83 TO 1120 ON SALE

SAN FRANCISCO via Shanghal, Japan Ports & Honolulu.

Wednesday, 16th October. Wednesday, 30th October.

SEATTLE, VICTORIA via Shanghai & Japan Ports.

TAIYO MARU

TENYO MARU

MISHIMA MARU

IYO MAEU

Monday,

Monday,

21st October.

4th November.

LONDON, MARSEILLES, ANTWERP, ROTTERDAM via

Singapore, Penang, Colombo, Suez

* KAMO MARU

*KATORI MARU

Saturday,

Saturday,

SYDNEY & MELBOURNE via Manila & Porta.

AKI MARU

KAGA 'MARU

AWA HARU ..........

19th October.

2nd November.

Wednesday, Wednesday,

23rd October. 20th November.

14th October.

27th October.

BOMBAY rin Singapore, Penang, & Colombo.

+ NAGATO MARU

Monday, Sunday,

tice.

said:

which

thon.

Keeping the little indicator pointer in the middle of the dial is much leas weurisone than keeping the compass card on a bring like 16 degrees south to west for example.

Disadvantages of Earth Inductor *

Compass

In presenting his subject Mr. Wills The earth may be likened to a very large permanent magnet having a very werk Bold and poles whose positions The two principal advantages of the are changing both continuously and earth inductor compass are that it may daily in short periods. The slow, con- be located in a place free from the tiguous change in position has been ship's local magnetic disturbances and predetermined for a number of years, that it is a very easy and satisfactory the diurnal variation is often notice thing to steer by, able in magnetic storms. The design er of a compass usually has several She has grievances against nature. not made the earth's fleld strong enough. Geld of roughly half a

A Rauss is the most that the designer can expect ami that has a direction which varies wver the whole surface of the world with perfect lack of co- operation on the part of nature. The component horizontal to the earth's Rurface is the only one which interests man in methods of navigation. Also, the direction of the magnetic north doen not coincide with that of geographical north,

From Seattle, Washington one looks 25 degrees to the cast of true north to look directly toward the magnetic pole. From Maine one must look 20 degrees to the west of true north.

This is a change of 45 degroes within the United States When flying in the State of Washington, the avia. tor must subtract 25 degrees from his compass reading to get true north, provided no ather

compass errors exist. This

regretthle

atate of affairs forces the

avintor

to carry a amall map

showing the ma

magnetic

etic declination.

Compass ErrorA Probably it will be helpful to in- felude a list of the errorsto which any type of magnetic compass is subject jed.

Those errors will be explained later. Declination, described above, will not be listed as an error. It is nature's histake.

(1) Ship's magnetised iron.. (2) Ship's unmagnetised iron.

(a) Unsymmetrical in the horl

zontal plane.

(b) Unsymmetrical in the verti-

cat planes.

(3) Acceleration errors due to com pass card being suspended as a Den įdulum.

For aircraft magnetic compasses, it

1. It requires a universal joint to This transmit, torque to the rotor.

niversal joint must be well inade if it is not to disturb the vertical position of the rotor.

2. The amount of voltage generated. ficulties are encountered. Lubrication is very small and commutation dir is resorted to to keep the commutator clean and to prevent excessive wear on the commutator. Neglect of this lubri cation in proper amount caused the carth inductor compass fitted on the "Southern Cross" to become ineffective during the flight to Australla.

3. It is n complicated and costly in strument. The armature has thousands of turns very fine wire I wound upon a non-magnetic support made of wood or other suitable mater inl. This gives it a high moment of inertia and makes it very cumbers some. The instrument adds consider. able weight to the air-craft. It is also necessary to make the diameter of the rotating meniher large.

many

4. It is subject to all the accelera- tion errors of the ordinary magnetic card compass, but due to its meenani- cal arrangement it lends, itself to bet ter damping. Also it may be subject to errors or possession' due to gyroscopic nction.

5. Errors due to brush ft are liable to occur.

The advantages of the earth indue- tor compans are very important ones and

way Was

sought of Home

dls-

to overcome

itu

advantages. It occurred to Dr. J. D. Tear of our Research Laboratory

But

compass, the accuracy of the course depends upon the position of the brushes. Wear of brushes, which covered nearly twenty degrees of the commutator when carbon brushes were used, would cause quito! serious error in the course indicated. Even with silver brushes this error

18

error is absent in the magneto type of serious. Obviously this source of compass where the course indicated depends only on the relation of the polc-pieces.

lowing advantages:-

The magneto compass has the fol-

1. No universal joint.

2. The stabilized part does not

rotate.

3. Greater sensitivity or voltage due to the high permeability of the permalloy bars.

1. Accuracy is not impaired by

brush position or brushwear.

5. No commutation difficulties.

6. No oiling or maintenance required due to small parts and very low commutator peripheral speed. 7. It is much smaller and lighter than the old type of earth Indur- tor compass generator. from the laboratory stage and test The magneto compass has emerged bench stage and to being tested in the air. So far, it has not developed any faults of a fundamental nature.

WARSHIPS HERE

The following warships harbour this morning:

SATURDAY, OCTOBER 12, 1929.

FAST LUXURIOUS

SERVICE

-to America

TRAVE

and Europe

RAVELLERS bound for America or Europe avail themselves of speedy and corn- fortable service when they go Canadian Pacific.

The White Empresses are the largest, newest and fastest liners on the Pacific. They cross from Yokohama to Vancouver in 9 days; from Shanghai to Van- couver in 14.

These ships connect with the summer trains, Trans-Canada Limited" and "Mountaineer," at Vancouver, enabling - passengers to make the earliest sailing of a Canadian Pacific Atlantic liner.

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Next mailing to the Pacifle Coast

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S

NOON=31st October 1929,

LATEST TRAVEL

SYSTE WI

BRITISH WUCHOW LINE

SAILING DATES FOR OCTOBER, 1929 (Subject to change). DEPARTURE HOURS: Hong Kong 5.30 p.m., Wuchow 1.30 p.m.

S.S. TAI HING" [1,008 tons Capt. Troft.]. OCTOBER

S.S. "TAI MING" [649 tons-Capt. G. J. Spink] OCTOBER

SUN. 27th

MON. 14th THURS. 24th WED 16th

TUES. SAT. 19th

29th MON. 21st Regular Service of Fast, High Qluss River Steamers Having Good Ac- commodation for First Class Passenge's Electric Light and Fans in State- roome and Saloon. The s.s. "Tai Hiag" la fitted with Wireless.

These vessela leave Hong Kong for Wuchow (via Samahul, Shishing, Takhing & Dosing) and return to Hong Kong (via same Ports) every Ave were in aya.

In the Basin: H.M.S. "Tamar," "Sandwich," L. 20 and L. 10.

North Arm:-H.M.S. "Titania" and L. 15.

West Wall:H.M.S. "Berwick."

In Dock:-H.M.S. "Tarantula,” L. 8,; L. 33 and L. 27.

No: 6 Buoy:"Seraph."

- No. 4 Buoy:—"Herald." No. 6 Buoy:-Sirdar." No. 10 Buny: "Stormcloud."

"Sterling" and

No. 11 Buoy:Thacian Sepoy." No. 12 Buoy:-"Serapis." No. 13 Buoy

"Bruce."

Foreign Men-of-War •

is parctical to provide compensation that the earth's field might be intensi, )、 only for any permanent magnetiam fed or concentrated by means of 'some due to the magnetised parts of the ship. The location of the magnetic compass must be in front of the pilot some at the low magnetising forces exerted "John Edwards," where on the dash board. This is by the earth's field. Worse atili once

SOUTH AMERICA (West Coast) via Japan, Honolulu, Los Angeles, usually about the worst magnetic posi-

Mexico & Panama,

GINYO MARU

Tuesday, 29th October.

SOUTH AMERICA (East Coast) vin Singapore, Cape Town & Forts,

HAKATA MARU

Wednesday, 23rd October.

NEW YORK, BOSTON via Pamama.

+ TSUYAMA MARU

Thursday, 24th October. LIVERPOOL via Port Sald, Constantinople, Genoa.

***... Sunday,

·† TOYOOKA MARU

TRANGOON MARU

t.CEYLON MARU

SHANGHAL KOBE & YOKOHAMA.

KASHIMA MÁRU

-KAGA MARU (Nagasaki direct)

WAKASA MARU (Moji direct)

17th November. CALCUTTA via Singapore, Penang & Rangoon,

Wednesday, 10th October. Tuesday, 29th October.

Monday, 14th October. Tuesday, 15th October. Wednesday, 16th October.

+ Cargo only.

Reduced 1st Class Excursin Fatas quoted between Manila and Australia.

For further information apply to-NIPPON YUSEN`KAISHA.

Tel Central No. 202, 3897 and 8821, (Private exchange to all departments.)

0

S. K.

BAILINGS FROM HONG KONG SUBJECT TO ALTERATION.

AMUR MARU

LONDON, HAMBURG, ROTTERDAM & ANTWERP VL Singapore

Colombo, Sues and Port Said.

Wednesday, 6th November, RIO DE JANEIRO, SANTOS & BUENOS AIRES Via Saigon, Singapore,

PUSA 13 Gelombo, Durban & Cape Town.

SANTOS MARU. A

BUENOS AIRES MABU ........

BOMBAY Via Blagapore & Colombo.

SHUNKO'MARU ...

HONOLULU MĀRU

↑ (Calls at Karachi),

Friday, 1st November.

Friday, 22nd November.

Sunday, 20th October,

Sunday, 3rd November.

DURBAN, LOURENCO MARQUES, BEIRA, DAR-ES-SALAAM, ZANZI.

BAR & MOMBASA-Via Singapore & Colombe..

PANAMA MARU ..........

Bunday, 27th October,

CALCUTTA--Via :Singapors, "Panang de October.

BORNEO HERBERT

SEATTLE MARU

Friday, 1st November.

magnetle material such as iron. iron has an extremely low permeability

magnetised, it tends return this

U.S. Destroyers" "Whipple"

and

French Gunboat "Vigilante." Italian Gunboat: "Sebastian"

tion on the ship, due to the engines. magnetism, It has a high coercive Cabote," control columns and stray felda from any other electric meters. A single electric meter containing permanent magnets is sufficient, when installed near a compass, to render it valueless. The Earth Inductor Compass Some sort of remote indicating com- ing forces include fairly large con dress at the College of Pestology, pass was desired so that a mora fa- centrations of flux in the metal. And Bedford-square, by Mr. A. Moore vourable magnetic location could be what is even more important. Chis used. Such a favourable location may strange alloy has negligible coercive Hogarth, who suggested the use of medicated dust in bog and usually be found in the fuselage just force, that is to say, when the very marsby breeding grounds for the forward of the tall, oven though the amali

magnetising force is removed members in the tail be of steel. These from its vicinity, the magnetic flux dis- absolute extermination stoel members do not distort the appeara almost completely.

Hereln pest. earth's field to any extent twenty-four ties the clever conception of this very inches from them. provided they are original and important Invention. Dr. This fear proposed and developed an earth not permanently magnetised.

inductor compass using permalloy, a metal composed of 785 per cent, nickel and the remainder iron. This compass

force. Those considerations led him to the nickel-iron alloys such as per- malloy which have the desired pro- The mosquito menace, which is perties at low flux densities.

stated to be steadily increasing in Permalloy has such a very great Britain, was the subject of an ad- permeability that very small magnetis-

need has given rise to the development

of the earth inductor compass.

The earth inductor compass consists

The Magneto Compass

of a direct current armature of non-is called "magneto" compass. magnetic material and brushes. It uses the earth's horizontal component

Let us assume that a bar of per of field for excitation. The indicator malloy is stabilised in the horizontal is a censitive micro-ammeter with its plane. It is always necessary to ex- zero position midway on its scale. The clude the vertical component in any rotor must be pendulously supported type of magnetic compass. If the bar to keep ita axis vertical so as to cut is pointing east and west, that is, if it only the horizontal component of flux. is perpendicular to the magnetic meri- If disturbed from this vertical position dian, the earth'e fold induces no Bux the rotor then has a voltage generated in the bar along its length. If it is now due to the vertical component of the deviated slightly, from this East and earth's Bald. This voltage gives a west position, a flux is induced in the false indication of direction. In this bar along its length. The intangible my titsbject to exactly the same lines of force in the surrounding space accelaration errors as the card com-are sucked into the pealley and find The 10tor is driven through the shortest and easiest path...to be universal joint: Since torque must be along the metal. The amount of flux transmitted through this universal passing along the axis of the bar de joint, it may become a source of error ponds upon the angle of orientation inasmuch as the rotor will tend to line and increases until the bar lies in the up with the driving shaft, whether or magnetic meridian., That is, when the not this is vertical.

To set a course the brushes are magnetising force is a maximum. The direction of this flex depends upon rotated to such a position with res which way it is deviated. This flux la pect to the earth's magnetic field that detected by inserting a small rotating the voltage generated in the various colly adds up to zero. As long as this section of perualley in the middle

the main bar. Upon this small rotu cuareo is maintained the indicator ruting section in wound coll of wire. msins at zero. If the pilot deviates This constitutes a small two-poler arma from the course to the right, the indi- ture which in caused to, spin' about a cator has arbitrarily a positive cur vertical axis--an is fixed with re

VICTORIA, BEATTLE, TACOMA & VANCOUVER Vin Japan Forts from rent through it due to the new position spect to the aircraft. The two bars

** Bhangkal.

PARIS MARU (From Shanghai) Tuesday, 15th October,

MELBOURNE--Via Manila, Brisbane & Sydney.

HIMALATA MARU

HAIPHONG.Vn Habo IPho

MENADO MARU

NEW YORK-Vin Japan ports, San

DAN: ABGUN/MARU. -...

JAPAN, PORTS

CELEBES. MARU

GANGES HARU

KEBLUNG-Via Eustow & Amoy,

CANTON MABU.

HOZAN MABUNGA TAKAOSVIERVATOW &. AMOY,

Thursday, 7th November,

Thursday, 17th October, 10 Francisco & Pandiwa.a

Monday, 28th October,

Thursday, 24th October.

a.m.

- Sunday, 13th⭑October......

Sunday, 18th October, Noon, Sunday, 20th October, noon,

Thursday, 24th October, 10 am.

Sunday, 18th: Detöber. plouse, sosiy to--OSAKA SHOBEN KAISHA. ©Tel Contral, No. 4088, 4089, 4094,

KACIJEKELUNG:

BATAVIA MARU,

-M. TAKBUCHI, Manager,

of the brushes with respect to the are stabilised about the centre of the earth's field. If the deviation from the rotator that they may lie in a hoti- course is to the left, the current in contal plane whether not the rotor arbitrarily negative and the Indicator axis is exactly vertieni.This is effect! so recorda. The brushes are geared ed by attaching the transverse axis of pozmanently to an azimuth ring grad- the bars to a pendulum The bars thus usted into points of the compasso muunted on an axle are prevented from that when the indicator registers zero, diaturbing oscillations in the vertien a glance at the azimuth ring, ind cates plane by a damper. The rotor is al- the position of the brushes and the most perfectly shielded from any out- course. The azimuth ring is located side flux by faring the pole tips, only on the dash or within easy reach of the permitting that flux which passes along pilot. When the pilat wishes to change the length of the bars or pole-pisces to a new course, he simply turns tha to pass into the, armature. · The spli- azimuth ring on this dash board to the ning: rotor cuts the flax which fa due. desired indicated course. Through to the orientation of the bars and gos- Anxible cable drive this shifts tha prates an ein.. in the coll: The ami. hrushes with respect to the earth's in led to a very tiny-two-bar commuta- fald. To bring the fadicator back to for, where, it is reculled. Even the zero; "that brushes must be brouge: | movement of the bars through. haf ai

of

the

Faren*for round trip (not including meals) $20. Meals & Wings are o be obtained on board."

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