Site planning in practice; an investigation of the principles of housing estate development

Front matter

WrJ.

X.

ACCESSION

Foreword

The conviction has been growing during recent decades that more care than has hitherto been considered necessary should be taken to secure the proper use of land, and that greater skill should be devoted to the laying out of building estates and to the orderly development of towns. It is now realised that the best results are not obtained by submitting tamely to the vagaries of haphazard growth, but can only be secured by the exercise of foresight in the distribution of the parts of a town, and in the considered arrangement of the roads, buildings, and open spaces upon each site. But, both in the larger sphere of town planning and in the more detailed branch of the work which is concerned with the lajdng out of residential areas and which may for convenience be termed site planning, there is ample need for further study of the conditions and possibilities. Hence Mr. Longstreth Thompson has performed a valuable service in compiling a volume in which reliable information, considered principles, and established practice are assembled and co-ordinated by one who is well qualified by training and experience to select from the large amount of material available that which should be included, and to reject much which is still too tentative or experimental for the purpose in view.

In addition to dealing with the more usual branches of the subject, Mr. Thompson has pursued several original lines of inquiry. There are, for example, some interesting statistics as to the various types of business, public, or semi-public buildings normally associated with a given population, which should prove a valuable guide in estimating viii FOREWORD

the provision that has to be made for these purposes in the development of new residential areas. And there is an instructive analysis of the effect of different densities of development on the most convenient and economical shapes and sizes into which land can be subdivided by the roads.

Mr. Thompson, in his book, shows how experience has proved the essential economy of open development. The percentage of the total population for which this method provides the most suitable residential surroundings has yet to be determined. It seems clear, however, that the limit in this direction has not yet been approached, and that, meantime, both economy and other considerations of social welfare suggest the importance of providing every new house with sufficient ground for the cultivation of a small garden.

In spite of the fact that there may be found many good examples of comprehensive site planning carried out in the past, we must admit that, generally speaking, the building development of the last century reflects no great credit either on the intelligence of land owners, or the skill of their technical advisers. Frequently the development has not even had the merit of being economical, and where it has been economical in a certain sense, too often advantages of an outstanding character and amenities of permanent value have been entirely sacrificed to secure a quite minor and temporary monetary advantage. The importance of devoting care and skill to the laying out of all lands which are to be used for human occupation cannot easily be exaggerated, especially in view of the permanence of the conditions which are thereby estabhshed, and it is to be hoped that Mr. Thompson's book will contribute to the realisation of the character and importance of this work, as well as help to improve the general standard of practice in connection with it.

RAYMOND UNWIN.

Introduction

The subject of Housing has been approached from many different angles. Contributions to the common store of knowledge have been made from time to time by Sociologists, Hygienists, Architects, Landlords, Lawyers, and Politicians, concerning those aspects of the problem with which they are most closely in touch. It might seem, therefore, that but little scope remained for the breaking of fresh ground. But, although the field is already so well cultivated, there is still one corner of it that has not yet received intensive treatment. In this country, at least, no detailed study of Housing development as an integral part of Town Planning has hitherto been attempted, and it is in the hope of doing something towards filHng this important gap in the literature of the subject that the present volume has been written.

While it cannot be claimed that the newly awakened art of Civic Design has reached its full development, it must be admitted that considerable progress has been made in that department of it which is concerned with the planning of residential areas. A quarter of a century has elapsed since Mr. Ebenezer Howard advanced what were then regarded as his Utopian proposals for the establishment of Garden Cities, and it is many years since Mr. Raymond Unwin, among his many contributions towards the concrete realisation of better standards of housing, demonstrated the economic fallacy of " overcrowding." During this period much has been learned of the practical application of these once revolutionary ideas. The experience gained through the earlier experiments, of which Port SunUght, Bourn ville, New Earswick, Woodlands,

X INTRODUCTION

Letchworth, and Hampstead Garden Suburb are typical examples, has been augmented by that derived from the host of smaller enterprises undertaken by Public Utility Societies all over the country. In addition, the immense programme of the National Housing Scheme, initiated by the Government to make good the shortage of houses occasioned by the War, has provided an unparalleled opportunity for testing upon a large scale the value of many theories of Site Planning, not hitherto supported by evidence of a sufficiently extensive character to be altogether reliable. Thus, a large amount of valuable information concerning the technical problems of development has already accumulated, and it would seem to be, therefore, a particularly suitable occasion for an attempt to deduce from the experience now available such principles as may be found to have general application to the development of residential areas.

Unlike the majority of subjects upon which technical treatises are written. Housing cannot readily be isolated from its natural surroundings and subjected to a purely scientific analysis. The human element is so essentially part of its very structure that, even in a work primarily devoted to the technical aspects of the problem, it is impossible to avoid frequent reference to the philosophical and sociological questions which arise at almost every stage of the argument. For it must be recognised that theories of housing or town planning which are based upon no surer foundation than mere technical efficiency have but little chance of permanent success. If any proof were needed of this statement, it is supphed by the poorer residential districts of every modern town, where, in the absence of any civic ideal beyond that of an admittedly high standard of sanitary efficiency, there have grown up vast districts, " which," as Mr. Unwin has observed, " for dreariness and sheer ugliness it is difficult to match anywhere, and compared with which many of the old unhealthy slums are,

INTRODUCTION xi

from the point of view of picturesqueness and beauty, infinitely more attractive." " The truth is," to continue the quotation, " that in this work we have neglected the amenities of life. We have forgotten that endless rows of brick boxes, looking out upon dreary streets and squaUd backyards, are not really homes for people, and can never become such, however complete maybe the drainage system, however pure the water supply, or however detailed the by-laws under which they are built. Important as all these provisions for man's material needs and sanitary existence are, they do not suffice." A wider ^dsion is needed, in which houses are regarded as homes, and homes as part of that social entity which we caU the town. The business of the town-planner is to guide and interpret, as far as he is able within the limits imposed b}'' practical considerations, the civic needs and aspirations of those for whose material comfort and convenience he has to provide.

If this view of the matter is accepted, and there are unmistakable signs that it is coming to be regarded as the only reasonable attitude to adopt, it follows that all housing proposals must form part of a comprehensive policy of town development. Thus the investigation of the general tendencies of urban growth, and the detailed survey of the particular town or region in question, which are outhned in the first two chapters, will be recognised as preliminary studies essential to the due consideration of the problems connected with the choice and development of housing estates. For without a knowledge of the existing conditions and probable future growth of a town it is impossible to arrive at a clear decision as to the best means of making adequate provision for the accommodation of its steadily increasing population.

It will be observed that the methods of development examined in the following pages are based upon a building density of twelve houses to the acre. This figure is now so generally accepted as a reasonable standard, that its xii INTRODUCTION

adoption here requires no justification. But while no single factor has had so great an influence upon the details of Site Planning as this limitation of density, and valuable as are the results thereby achieved, it must not be assumed that the employment of a system of open development is the sole desideratum in the laying out of residential areas, for it is necessary to consider not merely the comfort and convenience of the individual, but also the general needs of the community. Hencfe the primary conditions which must be satisfied by the plan are, that its main outlines should fit in with the projected development of the town considered as a whole ; that adequate localisation of interest should be secured by the creation of a centre where the social life of the district would find a natural focus ; and that due provision should be made for the open spaces, public buildings, shops and other similar requirements of the future residents. These conditions can and, indeed, must be fulfilled irrespective of the building density, which, although a vital consideration from the point of view of health and amenity, is, so far as the development plan is concerned, a determining factor only in the arrangement of the minor roads. In this matter, however, the reduction of the density to an average of twelve houses to the acre has revolutionised the methods formerly in use. The greater freedom in road location and design, which is permitted by the increase in the size of the house plots, has resulted in the abandonment of the stereotyped system of parallel streets and in the adoption of the much more rational procedure of adapting the lay-out plan to the contours of the site. By this means not only is it possible to preserve and even enhance the natural beauty of the estate (for, as Dean Inge has observed, " We sometimes forget that until the reign of George III. a town was regarded as improving a landscape "), but also to effect considerable economies in the actual cost of development. Thus the criticism, frequently made at one time, that a reduced

INTRODUCTION xiii

density involved increased expense, is rendered invalid where the price of land is reasonable and care is exercised in preparing the plan. While if value received for money spent is a sound criterion, there can be no question of the economy of a system which secures to each householder all the advantages of a garden for the same expenditure as would previously have been necessary to provide a mere backyard.

The full advantages of such a system, however, cannot be achieved under the regulations hitherto enforced in regard to the construction of roads and sewers in the majority of our towns. These were designed to protect the citizens from the worst features of a type of development which, under a proper system of town planning control, can never be resuscitated. There is reason to hope, therefore, that at no distant date the modifications which have already been sanctioned by the Ministry of Health in connection with the Government Housing Scheme, and have stood the test of experience, will be incorporated in the by-laws of every municipality in the country.

In bringing these introductory remarks to a conclusion, I wish to express my gratitude to those whose kind permission for the reproduction of plans and photographs has made it possible to include among the illustrations representative examples of modern practice in the development of Housing Sites. My thanks, also, are due to Mr. Raymond Unwin, Mr. Thomas Adams, Mr. Eric Hayman, and Mr. A. Trystan Edwards, whose advice and criticism have been invaluable. Lastly, I must record my appreciation of the help and encouragement of my mother and my wife, whose labours in connection with the manuscript and diagrams have been of the greatest assistance in the preparation of the book.

LONGSTRETH THOMPSON.

121 Victoria Street, London, S.W. i.

Chapter I Page

Housing a Function of Town Planning ... . i

Towns of Excessive Size undesirable . . . 2

Circumstances determining most Effective Size . . 3

Arbitrary Limitation Useless ..... 4

Industry the Predominating Factor in Urban Growth 4 Industrial Centralisation —

Physical Causes . . . . . . 5

Inter-dependence of Industries . . . . 6

Transport Facilities ...... 6

The Supply of Labour ..... 7

Industrial Decentralisation—

Tendency to form New Industrial Centres . . .7

Housing Policy—

Addition to existing Town ..... 8

Dormitory Towns ...... 8

Satellite Towns . . . . . .9

Garden Cities ....... 9

CHAPTER n

Extent of Survey necessary for Housing Purposes . 11

REGIONAL SURVEYS Subjects of Investigation , . . . .12

XVI

Lessons from the South Wales Survey- The Effect of Physical Conditions .

The Trend of Industrial Development Housing Areas available Comparis'on of Alternative Sites Determination of Future Policy Practical Recommendations .

Ancillary Measures The Practical Value of the Survey

15 16 16

17 18 18 19 19

TOWN SURVEYS Scope of Inquiry ....

Graphical Representation of Results

23 26

Chapter III

THE CHOICE OF SITE CHOICE OF LOCALITY Position in Relation to Industrial District

Need for Houses both Near to and Distant from Factory

Limits of Choice defined by Transport Facilities . 34

CHOICE OF ACTUAL SITE Area required .....

Conditions requisite for Health Topographical Considerations .

Accessibility .....

Facilities for Water Supply, Drainage, etc. Economy of Development Partially developed Sites Cost of Land , , . , .

34 36 39 39 40 40 xvii

Chapter IV The Development Plan : Preliminary Considerations

GENERAL REQUIREMENTS

Provision necessary for Social and other Needs of Community .......

Data for estimating Probable Requirements

Economic Advantages of making Adequate Provision for Auxiliary Purposes . . . T . .

45 45

TOPOGRAPHICAL SURVEY OF THE SITE

Nature of Information required , . . .50

Survey should extend beyond Limits of Actual Site . 52 Survey Plans ....... 54

INITIAL STAGES OF THE DEVELOPMENT PLAN

Provision of Routes for Through Traffic . . 54 Disposition of the Component Parts of the Scheme—

Areas for Houses of Different Classes . . -56

Local Centre for Shops and Civic Buildings . . 56

Subsidiary Centres . . . . . .60

Educational Buildings . . . . .61

Places of Worship . . . . . .61

A Permanent Rural Belt . . . . .66

Chapter V The Development Plan : Classification

AND DESIGN OF ROADS

CLASSIFICATION AND DETERMINATION OF WIDTHS

The Effect of Building Density upon Road Planning . Classification of Roads ......

b

11 74

XVIU

Arterial Roads —

I'AGE

Total Width .....

. -75

Width of Carriageway .

• 75

Provision for Trams ....

. 76

Gradient

. n

Standardisation Undesirable .

. 78

Secondary Roads .....

. 78

Residential Roads —

Major Residential Roads

. 81

Minor Residential Roads

. 81

Drives ......

. 81

Turning Spaces ....

. 83

Gradients .....

. 83

Treatment of Roads on Steep Slopes

. 84

Boulevards and Parkways —

Character ...

. 86

Width and Treatment

. 86

ROAD CONSTRUCTION Construction determined by Character of Roads Kerbs and Channels . . . • 1 •

Carriageways—

Foundations ......

Surface ......

Footpaths .......

r

Margins .......

88 88

89 90

91 92

TREE PLANTING General Observations .....

In Main Roads and Boulevards In Residential Roads .....

Result dependent on Choice of Suitable Varieties

93 93

94 94

XIX

Chapter VI The Development Plan: The Arrangement

OF THE ROADS Types of Lay-out—

The Rectangular Form

The Spider's Web Plan

The Geometrical Arrangement

The Contoured Method Form of Lay-out determined by Local Conditions Essential Features of Road System .

Economy in Road Frontage —

Continuous Building ....

Gaps between Houses

Loss at Road Junctions

Concave Corners and Culs-de-Sac .

Effect of Density on Road Planning—

Arrangement .

Subdivision of Land into Building Blocks—

Proportions .....

Dimensions .....

House Plots .....

Street Orientation and Distance between Buildings The Special Problems of Hilly Sites—

Direction of Roads relative to Contours

Treatment of Regular Slopes

Treatment of Undulating Land

Treatment of Steep Slopes ....

95 96 98 98 100

104 104 106 108

114 116 116 118 122 124

130 136 141

CHAPTER Vn

WATER SUPPLY FOR RURAL SCHEMES

Quantity

XX CONTENTS

PAGB

Sources of Supply—

Wells 153

Stored Rain-water . . . . . -155

DRAINAGE

RURAL SCHEMES

Dry Method of Disposal . . . . -157

Liquid Wastes . . . . . . -157

Water-carriage System . . . . . -159

URBAN SCHEMES Existing Sewerage System ..... 160

Detkrmination of Main Lines of Drainage . . 161

Provision for Future Extension . . . .161

Location of Sewers . . . . . .161

Arrangement of House Drains—

Economy of Sectional Drainage . . . -163

Conditions requisite to Efficient Arrangement . .164

Responsibility for Maintenance . . . ,168

CHAPTER VIII The Value of a Co-ordinated Park System . .170

Nature of Requirements ..... 170

Allowable Area . . . . . . -171

Cricket and Football Grounds . . . -173

Lawn Tennis Courts . . . . . -173

Combined Facilities for Several Forms of Recreation. 173 Children's Playgrounds . . . . . .177

Decorative Function of Open Spaces . . .178

Open Spaces and the Occupation of Road Frontage . 179

XXI

GARDENS AND ALLOTMENTS

PAGE

Allocation of Land as between Private Gardens and

Allotment Areas . . . . . .184

The Placing of Allotments —

Arrangement and Appearance . . • .186

Private Gardens . . . . . . .186

Treatment of Forecourts . . . . .188

CHAPTER IX THE DISPOSITION OF THE BUILDINGS Necessity for Co-operation between Architect and

Site Planner . . . . . . .190

Use OF Natural Features to secure Distinctive Arrangement OF Buildings . . . . . .196

The Grouping of Public Buildings . . . .198

Civic Centres—

Village Greens ...... 198

Enclosed Places ...... 203

Buildings requiring Separate Locations—

Places of Worship ...... 207

Arrangement of the Houses —

Building Lines . . . • . .212

Considered Grouping . . . . . .213

Treatment at Road Junctions . . . .214

Terminal Features to Street Vistas . . • .219

Topography an Important Factor in House Grouping . 237

Provision of Secondary Access—

Semi-detached Houses with Side Entrances . . 240

Back Footpaths . . . . . .241

Passageways through the Buildings .... 243

Special Methods for Colliery Districts . . . 244

Aberdare —

Cwmneol Housing Scheme, plan

„ „ „ section .

Amersham —

Houses grouped on hilltop, general view „ „ „ near view

Building Blocks of various shapes and sizes-

1. Rectangular ....

2. Triangular ....

3. Trapezoidal ....

4. Segmental ....

Civic Centres —

Abercarn, Treowen Scheme Liverpool, Walton-Clubmoor Llay Village

Newburn-on-Tyne, Throckley Tremadoc, plan .

„ general view

„ near view .

Civic Survey Diagrams of York —

I. Distribution of different kinds of buildings

FIG.

PAGE a a

types of

residential

districts

.

5) »»

and

allot-

ments .

Communications

.

.

Time-zone diagram

.

.

.

Position of housing

sites

.

XXIV

Culs-de-Sac—

Burry Port, photograph Chesterfield, Halfway Eckington Folkestone, plan

„ entrance

„ way through houses

Hatfield, plan

„ photograph Oulton, plan Symmetry of, spoilt by levels .

Density Diagrams—

Twelve houses to the acre Twenty „ „

FIG.

PAGE

III Dormanstown

Aerial view

Drainage—

Filter trenches for rural cottages Sectional and separate, diagram

Gardens, Subdivision of- Diagram .

High Streets, Broad—

Amersham . . . .

Tenterden . . . .

House Grouping —

At road junction, diagram

At turning place in road, photograph Reflected in forecourts, diagram lOI

Kerb and Channel- Combined form .

XXV

Lay-out Plans—

Abercarn, Lan Fach

„ Treowen

Barry Garden Suburb .

Bellingham

Brighton, Moulescombe Estate Burry Port Garden Suburb Chesterfield, Highfield Hall Scheme Dartford ....

Dormanstown . .

Dover ....

Glasgow, Moss Park

„ Shettleston and Tollcross

Jordans Village .

Killestre ....

Leeds, Hawksworth Wood Scheme Lemington-on-Tyne Liverpool, Larkhill

„ Springwood-Allerton

„ Walton-Clubmoor .

Llay Village

Newburn-on-Tyne, Throckley Scheme Newcastle-on-Tyne, Walker Estate Nottingham, Sherwood Estate Portsmouth, Portsdown Hill Scheme Roehampton Sheffield, Manor Estate

„ Stubbins Estate

Swanpool Temple-Newsam Wakefield, Thornes Park Walton-upon-Thames .

Leeds—

Distribution of housing sites .

Position of Middleton Scheme relative to city

FIG.

PAGE

V

lOI

Letchworth—

Diagrammatic plan

XXVI

Liverpool—

Distribution of housing sites .

Market Places— Alfriston . .

Amersham . . . .

Bungay .....

Newark-on-Trent—

Position of scheme in relation to town .

NORBURY—

House Grouping, plan .

„ photograph .

Occupation of road frontage, diagram i » j> « 2

)) 3> )1 3

Recreation Ground—

Plan

Road-Bays —

Brighton, Moulescombe Old Oak Common Sheffield, Walkley Hall White Hart Lane

Road Frontage—

Causes of loss, diagram

Loss at corners, diagram ...

Road Junctions, Arrangement of Houses at-

Built-up corner ....

Feeling of breadth at .

Semi-built-up corner

Typical treatment of right-angled corner » i» )) »

75 176

III

IIO

XXVll

Roads—

Cross-sections of Arterial roads „ Boulevards .

„ Residential roads

„ Roads on hilly sites

„ Secondary roads

Roads at Right Angles to Contours, treatment of- Folkestone .....

Hatfield

Norbury ......

Roads Diagonal to Contours, treatment of .

Roads Parallel to Contours, „

33 29

32 28

54 52 55 53

49 48

79 87 82

85 80

134 132

135 133

Roehampton —

House Grouping, plan .

„ photograph .

Rye—

General view

81 82 83

190 191 193

Secondary Access to Houses — Diagram i. Back roads

2. Duplicated back roads

3. Back footpaths

4. Tunnels through houses

5. Paved recesses for coal

6. Grouped coal and ash stores

7. Service roads

8. Arrangement suggested by S. P. Taylor

Set-Back of Houses—

Burry Port .....

Leeds, Wyther House ....

Roehampton . . .

xxviii LIST OF ILLUSTRATIONS

Tees-side, South- ^,^^ ^^^^

Industrial areas and housing sites . . .11 38

Vienna —

Diagrammatic plan . . . . .26 71

Village Greens—

Goudhurst, Kent . , . . .88 199

Newark-on-Trent . . . . . 90 201

Welwyn —

Diagrammatic plan . . . . . 25 69

Handside Lane . . . . . . Frontispiece p

Chapter I

Housing a Function of Town Planning. — The unprecedented shortage of houses with which this country was faced at the termination of the War, brought into prominence many aspects of urban development which had not previously received adequate consideration. Of these, the problem of deaUng satisfactorily with the continual expansion of our large cities is one of the most important. Under normal conditions the process of extension had been so gradual and the agencies through which it had been effected so numerous, that it was difficult to realise how rapid this growth had become or to what unwieldy proportions some of our towns had attained. But the magnitude of the accumulated deficiency resulting from the almost complete cessation of building for a period of nearly five years, and the necessity for making good this shortage en masse, made apparent the desirability of pausing to consider whether the addition of large numbers of houses to already overgrown towns was the most advantageous method of providing the required accommodation. It was thus realised that a comprehensive scheme of urban development is the necessary basis of a satisfactory housing policy, and that the initial step in the formulation of the latter is to arrive, in each case, at a clear and reasoned conclusion as to whether it is better to enlarge the residential district of the existing town or to create a separate and self-contained unit. This decision, while it is of fundamental importance to the preparation of the housing scheme and influences every operation from the choosing of the site to the disposition of the buildings, has a further and far greater significance. It involves the adoption of a definite policy with regard to one of the most crucial problems of urban development, namely, what is the desirable size of a town, and how far is it practicable to secure it ?

Towns of Excessive Size undesirable. — ^There is little doubt that in many of our large towns the economic and social advantages derived from the concentration of population at an urban centre are to some extent neutralised by the great expense of providing the necessary pubHc services, the lack of space for industrial expansion, and the absence of that organic relationship between individuals and the community which is one of the best features of town life. What Cobbett described as the " Great Wen '* of London is, perhaps, the most striking illustration of the undesirable results to which uncontrolled expansion leads. Every one is familiar with the inconvenience and loss of time incurred in the daily journey to and from work by reason of the congested state of the traffic in the metropolis. But few realise what this loss of time means in terms of money. It is difficult to make an estimate with any approach to accuracy, but even upon a basis of computation which is manifestly an understatement of the facts the result is somewhat startling. Assuming, for example, that only one-tenth of the population of Greater London, or 750,000 people, waste each day in travelling one hour more than they would in a town of moderate size, and that the average value of their time is only is. per hour, the aggregate loss is £37,500 a day, or £11,250,000 in a year of 300 working days.

The effect upon industry is less obvious, but the gradual exodus of manufacturing concerns to new centres outside the metropolitan area shows that the high rates, excessive cost of land, and lack of room for expansion, which result from over-concentration, have outweighed the advantages to be derived from a central position.

Of a somewhat different character is the lamentable lack of interest in local government and local affairs generally which has resulted from the assimilation of towns and villages by the Great City. As William J. Locke has said in The Fortunate Youth : " A London borough, unlike a country town, has very little corporate life of its own. You cannot get up as much enthusiasm for Kilburn, say, as a social or historical entity, as you can for Winchester or Canterbury. You may perform civic duties, if you are public-spirited enough, with business-like zeal, and if you are a borough councillor you may be proud of the nice new public baths which you have been instrumental in presenting to the community. But the ordinary man in the street no more cares for Kilburn than he does for Highgate. He would move from one to the other without a pang. For neither's glory would he shed a drop of his blood. Only at election times does it occur to him that he is one of a special brotherhood, isolated from the rest of London ; and even then he regards the constituency as a convention defining geographical limits for the momentary range of his political passions."

Many other ill effects of excessive size, such as the virtual separation of the dwellers in the central districts from the regenerating influence of the open country and the mental stultification produced by living in the mean surroundings of dreary suburbs, will occur to the reader.

Circumstances determining most Effective Size. — All this goes to show that towns can grow too big, and that there is a point of maximum efficiency beyond which mere increase of size operates adversely. At what stage of development this limit is reached is a matter requiring much closer investigation than it has hitherto received ; it is quite obvious, however, that there is no " one best size " appHcable to all cases. The variety of interest and occupation necessary to the full enjoyment of social intercourse, for example, will not be secured in a town, depending principally upon one industry, at the same limit of population that would be adequate in a town possessing varied industries. Regarded from the standpoint of health, also, it may happen, as in the narrow Welsh valleys, that the land adjacent to a town is unsuitable for housing purposes, and this fact will exert a limiting influence entirely absent from the majority of cases. Again, from the economic point of view the variation in conditions at different places often determines what is the best size for efficiency. Thus the cost per head of water supply would be a restricting factor in the case of a town which was approaching the limit of its local supplies, and which could only increase its consumption by tapping a distant source at great expense. In a similar way the difficulty of sewage disposal might set a limit to the size of a town situated on flat, low-l5ang land at some distance from the sea, as, for example, in the Doncaster area, while it would not affect a seaboard town at all.

Arbitrary Limitation Useless. — But, apart from physical factors, the growth of towns is so much a matter of human psychology that no arbitrary limitation of their size can have the least chance of success. Hence, before coming to any conclusion in the matter, it is necessary to study carefully not only the circumstances of any particular place, but the general tendencies of urban growth.