1948-04-29 — Page 8

མ་་

Technically

We believe that the only way to build a receiver is to begin at the beginning with a sound circuit design—a design that's been tested and re-tested-a design that. will stand up to the most critical examination. From this design a prototype la constructed in which every component receives the same rigorous testing. Wo leave the experts to pass judgment on the resulting Sobell receivers. We are confident that for ease of control and absolute fidelity of reproduction theso models will be found to have no equals-Chat, in fact, you will pronounce them Lo be technically outstanding.'

outstanding

SOBELL MODEL 516

T.C. TABL 2 RADIOGRAM

Roll top gives easy access to gramophone turntable. The receiver is a 5-valve super-het. operating fron 100, 200/260 volts, 40/100 cycles per second A.C. sup- ply. Wave range: 13-35 metres 35-100 metres & 103- . 577 metres.

AT SPECIAL PRICE

H.K. $500.00

ONLY LIMITED QUANTITY AVAILABLE.

JOBELL

LL RADIO

TWO YEARS' FREE ALL-IN SERVICE IN THE HOME Sért, a Schol! Indvatzier tid. Longlas Park, maer Slowght, Bucks.

SALES & SERVICE DY

WING TYER & CO.

23, Connaught Road C., Hong Kong.

Tel. 34363.

"YORK"

REFRIGERATION AND

AIR CONDITIONING EQUIPMENT

THE JARDINE ENGINEERING

CORPORATION LTD.

14-18 PEDDER STREET, HONG KONG,

Telephone 30011,

BRITISH DEUTZ LIMITED

"CAUSEWAY"WORKS, STAINES, MIDDLESEX

Spare parts for 5, 7 & 10 H.P.

DEUTZ HORIZONTAL ENGINES TYPE MAH 711-714-716

Available ex Stock in England

YU TUNG TAI LIMITED

Engthaaring Department

Aganta: for: Hong Kong

816, Queen's Building,

Griffith: Ballding, Ahul Woh Road, Telephone 13794, CANTON

THE CHINA MAIL, THURSDAY, APRIL 20, 1948.

ENGINEERING PAGE

SHELL CONCRETE BUILDING CONSTRUCTION

The principat features of shell concrete construction

were dis- cussed by Mr. H. G. Cousins. B.SS.. M.I.CE., in a paper foad before a meeting of the Reinforced Concrete Association held at the Institution of Civil Engineers,

Following is a summary of the speaker's remarks:-

Whilst the arch form shedate rainwater quickly from the aur- face and the shape and flexibility of the structure minimise crack- ing. It is not possible to guaran- tee the roof to be entirely free from haircracks, which might allow rain to penetrate. Water- proot coverings are therefore necessary for roofs which must felt or asphalt may he used. be impermeable. Either roofing

The essential feature of shell concrete construction is the use of suitably stiffened this concrete surfaces to span large areas. The

The problem of heat Insulation use of members subject to bend of shell structure is similar to int la uneconomical, since unly that of a normal reinforced con- the extreme fibres of the section Crete roof. The smaller thickness can be stressed to the allowable of stab used makes little differ- limits. In shell construction the without adding

dence to the heat transmission. covering itself 13 used

ony insulating 10 material, the heat transmission

roof transmit loads to

the

supporis.

It does this by means of direct would be about 18 BTU/sq. ft forces lying

wholly within the hour/deg. F. Where addi- surface of the root. For this re- of the standard methods can be tional resistance is required any sot the dead-weight does not in-

One of the simplest is

crease appreciably as spans be-opte

adopted.

large

conte larger, the thickness of the the use of building board as per- shell being determined by con-ment shuttering on the under- Half-inch soft board will siderations of bucking. This is of side. particular Importance In

reduce the transmissions by halt. span structures where the dead-ed either in the form of potent Roof lighting can be incorporat- weight is often a considerabid por- tion of the local weight

concrete to be lazing or

and glass carried.

lights.

These can be of almost any size and shape. While they can be placed in any position, it is usually most conventent and elcient to put them at the crown of the barrel.

Loading Teats.

Many loading tests have been carried out on shell roofing, both on models and on full size struc- tures. The defection mensured show clearly that these roofs act In accordance with theoretial cul- culations.

Patent glazing allows more light to enter than gloss lenses, but the latter are valuable in that they diffuse the, light more evenly. The good quality of the Such tests have been make both lighting is a particular feature with uniform lond over the whole of their buildings, which are free barrel or with a load on one side from the members and other qb- thly of the arch. One such test structions, The reduction carried out on a model 40 ft. lighting area necessary is useful long

15 ft. wide, with a shell, in reducing heat losses. An orcá thickness of

of 1.1/16 apply 62 lb. per sq. ft. on one, floor area is rufficient for most te of lighting equal to 4th of the side only of the barrel without purposes.

was

any cracking being observed.

Under each a loading the usual type of arch construction would have failed.

the

Ventilation

in

Louvres can be incorporated in

от

To allow for temperature move- ments in shell roofs, joints must provide natural ventilation. This the design of the roof limits to be provided in all straight mem- can also be achieved by louvred bers at suitable intervals, depend- panels in the end frames ing upon the flexibility of the standard type extracts through supporting columns. Such straight the roof. members are the shell in the Normal concrete and concreting direction of the generating lines, methods can be adopted for shell.

edge beams and also the end frames, if

these

are-straight agerehree-quarters of an inch suitable, although the These considerations limit

the m

maximum size la uften reduced of a barrel between end to 16 in. for the roof slabs. Grad-

bo selected to

work- ensure good ability, as many, of the section are small. Highgrade cement is us- ually called for. For small spons a 124 mix is sufficient, but for large spans richer mixes are used. of arch Ant in the majority of concrete work, normal mild steel round re- inforcement is usually the sim- plest to use. The fixing is easy and relatively cheap, although at first glance the detailing appears

to about 200 ft. A series ing and type of aggregate should

of parallel barrels can thus pro- vide a clear floor of up to 200 ft. wide and of inde@nite length.

I clear spans greater than 200 ft. are required, it is necessary to use the short barrel type sup- ported on end frames form having sufficient flexibility. Again, an indefinite length con be covered without colurnus ob- structing the clear width thus ob- tained,

G

Perkins

DIESELS

A Power Motor Crulier

Twin Perkins P6 M Engines.

F. PERKINS LTD.

MAKERS OF

་་

VEHICLE, MARINE & STATIONARY

DIESEL ENGINES

SOLE AGENTS

GILMAN & CO. LTD.

ENGINEERING DEPARTMENT

Talophones 21149:-

BUILDING HOUSES WITH A SPRAY GUN

palla

An entirely new.building material which can be prayed up to eight inches thick on to wire mesh, and sets within fifty- minutes, has been developed by the British firm of C. and T. Painters Ltd. of London. The material, "Pyroo", is made from lime, cement and Vermiculite. It is non-tracking and it will stick to wood or metal: It sets hard, but it will taks nails or screws

ews and can be cut with an ordinary saw. For wae on the outside of buildings it can be made waterproof, but in its normal state It absorbent so that 10 conden. sation occurs in the most 'muggy weather. Any necessary repair can be made with the

apray gun, and a walt of only three hours is necessary before the sprayed-on material can be painted. The combination of Pyreo with wire mesh may well mean now shapes for our homes with their main shells completed at a fraction of their present day cost. The most Important feature of the material; apart from its adaptability to all forms of bullding, is that it la fraproof. So low. Pyroc in heat conduction that. a blow-lamp may be

played against one side of a section ons Inch thick, and in can hold his hand against the other side without discomfort. A thickness of three inches of the material round a steel girder will prevent the girder sagging and bending ไป * burning building..

Top picture shows The Pyroc treated side of a structure stands - undamaged, although the petrol-worked. furniture in it. has burned away. The untreated alde has collapsed, completely gutted. Below is shown the technique of building a Pyroo wall.

complicated. Much of the rein- signs has enabled a number of forcement is in straight lengths, buildings to proceed. The factor and in the shell slab the small which ensures the extended use diameter bars used can be cur lot shell in the future is the pleas. ved on the roof as they are fixed. [ing, often impressive, appearance Several layers of reinforcement of the completed structure, which are used in the slab, some to take renders it attractive both to the the bending stresses in the shell, designer and building owner. while normally trajectory bar

pro ured following the lines of the principal · tenalle stresses. Where the latter are small, it is possible to reinforce with a mesh of steel, but this is not appreciably cheaper, and is less useful in preventing cracks.

Clean Lines

Although shell construction can be used with any structural ma terial, it is the only method by which large areas can be covered economically with concrete. A shell structure has all the

Cof..

Buch

concrete construction

ad permanence, strength against accidental damage, resis- tance to fire and lack of upkeep costs. The clean lines which may be obtained have both psycholo- gical and hygienle advantages. No greater constructional height needed than with other forms of construction. Good lighting and Insulation can readily be QB- thined. Point loads applied to the structure are not 觀 danger as with many other types of roof. Economy of material obtained, especially steel as

as compared with theweicht nocess materiais |

structure. No

for a steel

or methods of construction, other than those normally used in

concrete work, are neces- inforced on the designs should sary

entrusted to engineer specialising in the design of such the work on the side

structures, can, be

an

out by any repute. able contractor used to dealing

construction are

with Millies... of As the teak becoming widely known, increasing interest being, thown in its, develops ment for many types building Present Conditions" relciet many projects, but the low sel weight required for shell construction compared with, that for m

Esterlude:

Farnsworth

ALL WAVE BAND SPREAD RADIOS

MODEL GT-669-WAZ

Thoroughly engineered to provide lasting satisfaction, this advanced receiver offers the exclusive new Farnsworth Band-O-Lite tuning dial. Taking all the guesswork out of station determination, the Band-O-Lite Dial completely Illuminates the rospective wave band selected, enabling the operator to arrive at the definite frequency shown at the intersection of the lighted band Indleator and the station selector. Five wave bands including standard, tropical and short wave reception. Band spread. Cabinet styling has been patterned to complement the advanced chassis design.

FIVE WAVE BANDS FROM 535 to 1605 K.C. and 3.0 to

23.0 M.C.

EQUIPPED

WITH MULTI-TAP UNIVERSAL POWER TRANSFORMER FOR OPERATION ON A.C. 50 OR 50 CYCLES WITH LINE VOLTAGE SELECTOR FOR CHOICE FROM 105 TO 250 VOLTAGES.

FARNS WORTH— KNOWN FOR TONE

THE SINCERE CO., LTD.

SOLE DISTRIBUTORS

NEW Dictograph INTERCOM

MADE FOR

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THE SYMBOL

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Central Radio & Electric Co.

60 Nathan Road, Kowloon. Tel. 59814.

(OPEN