The existence of a single control over a large proportion of the men is a great advantage .sx The company has in practice taken further steps .sx Over one-third of its tally holders are in fact " preference " men , with the first claim to work , and endeavours are made to provide the number on the full weeks' work the year round .sx The system of using a number of preference men existed before the war , though not under that name .sx The company then had a number of registered workers to whom they gave cards at one period three hundred , but the numbers slowly rose to four hundred or more .sx Secondly , the other " shed call men " are called on a rota system in order of their numbers .sx Each man has thus a regular opportunity of being called , though the amount of work offered at any moment may be a full shift or a half-shift as the case may be .sx The purpose of this scheme is to equalize the chances of work .sx This method is not used by other employers in the port .sx The origin of the seasonal variation need not detain us long .sx It is less marked than in the other two trades , though its influence is exerted in other directions than actual unemployment .sx The summer demand of the Atlantic traffic and cross-Channel freight traffic is partly offset by the South African traffic in the winter .sx We ought for full understanding to distinguish between the separate types of labour demand which make up the aggregate demand ; for not only does a given change of passenger tonnage mean a smaller variation in the demand for dock labour than a given change of freight tonnage entered , but different classes of freight require different amounts of handling .sx It is not easy , in post-war years of wide trade dislocation , to set forth a description of " normal " trade behaviour , but in freight traffic certain features may , nevertheless , be noted .sx Potato imports are at a low level at the first four or five months of the year , rise suddenly to 400,000 tons in June , and drop in July to 10,000 and even 4,000 tons .sx Fresh fruit , on the other hand , shows a low minor peak of some 6,000-8,000 tons , and rises to its maximum in September .sx and October .sx Wool imports may be slow in the summer months but rise in October for several months .sx It is of such variations that the aggregate demand of the freight traffic is compounded .sx To what extent do the seasonal changes of demand and the methods of labour engagement together involve a pool of partly employed labour ?sx What kind of reserve does the industry " need" ?sx How much does it actually carry ?sx Such questions are notoriously difficult to answer .sx How are we to gauge the size of the surplus ?sx By comparing peak employment with average employment ?sx Or is it the excess of the numbers of tally holders over the numbers paid wages ?sx In the latter case , should we not have to consider also whether the earnings of the marginal group were large or very low ?sx In any case a percentage of idle tallies would have to be allowed for sickness .sx We may commence with the figures of unemployment .sx The absolute difference between the highest and lowest weekly figures of unemployed dock workers remains fairly steady , with one exception , despite the disturbed conditions of the trade and the advancing depression :sx Neglecting the exceptional year , the range of variation is thus between 7.8 per cent and 13.7 per cent of the insured population , and the average maximum variation thus 10.6 per cent .sx If we take not the highest weekly difference in each year , but the difference between the average weekly figure in January and in August , the figures are 1927 , 143 ; 1928 , 143 ; 1929 , 47 .sx Thereafter the movement is obscured by the upward movement of unemployment as a result of the world depression .sx These figures give us an idea of the range of variation amongst the whole insured population of the industry .sx What do we know of the smaller groups of tally holders ?sx Unfortunately our information is far from complete .sx A census or sample enquiry covering all tally holders , by whomsoever employed , is really required if the situation is to be fully understood , but an investigation of this sort was impossible .sx For the staff of the predominant employer , the Southern Railway , the amplitude of the seasonal swing this time tested by the numbers and proportions of the tally holders actually paid wages would appear to be as follows .sx In 1927 , in the rush month , the number of men employed was 86.7 per cent of the number of tally holders ; the average daily number employed was over 65 per cent of the tally holders in six months of the year , and under 65 per cent in the rest .sx This general average , however , over-simplifies the problem , for it is of its essence that the demands are variable and that the peak demand must somehow be satisfied .sx In twenty-one days in June , the busy month , the numbers paid wages were over 70 per cent of the total number of tally holders ; in four other months in more than one working day in every three the proportion of tally holders paid was over 70 per cent , and there was no month in which the demand on several days did not reach this proportion .sx It can be further tested :sx How frequently did men " miss their calls " for work ?sx We should have to exclude all vacant tallies from such calculation , and remember that some percentage must be allowed for sickness .sx Excluding all cases of the former , during the first six months of the year there were at least twenty-six days in which the number of men who missed their calls was ninety and upwards .sx In four rush days of June 178 missed one call or more and 73 missed both morning and midday calls .sx In another week of the same month 233 men missed one call or more .sx In the previous week 232 missed one call or more , and on one day in that week 164 non-tally holders were employed .sx We do not know the reason for the absences , but June is a busy month and whether the men are strictly allowed to do so or not , it is difficult to avoid concluding that some of them must have been due to opportunities of work being taken up elsewhere .sx The final test we may use is wages earned .sx To what extent have the steps taken towards decasualization stabilized the men's income ?sx How far did the seasonal changes of demand show themselves in pay ?sx Here again our information is far from complete , though it is available for the Southern Railway .sx As already stated , this company , besides its permanent staff , has 600 " preference " tally holders , a number of stevedores and shed call men engaged on a rotation system .sx Taking a typical pre-depression year 1927 , the total wages paid to the company's tally holders during the last four busy weeks of the half-year ending in June was 75 per cent greater than the amount paid in the first four weeks in the year , and 69 per cent greater than the amount paid in the last four weeks of the year .sx The seasonal swing is naturally greater than that shown by the numbers employed daily , since the latter figures do not indicate the length of the engagement or the amount of overtime worked .sx The average weekly wage of all classes of the 1,500 tally holders in this year was 2 13s .sx 7d .sx , but the range of variation was from an average of 3 1s .sx 6d .sx per week in the best months to 2 8s .sx 7d .sx in the worst .sx These figures include the earnings of preference men and shed call men , whose work is rather less regular .sx For example , the average wage per week of the preference men of various types was 3 9s .sx 2d .sx , while the figures for the best month were 3 16s .sx , and for the worst 3 4s .sx 3d .sx For these men two-fifths of the total number the arrangement has secured a substantial stability of employment and income .sx As regards shed call men , it was possible to obtain information in fifty cases , a sample of one in ten .sx In the six summer months , April to September , the average weekly earnings were 25 per cent higher than the earnings in the succeeding six winter months .sx The average for this group was 1 13s .sx 2d .sx for the summer months , and 1 6s .sx 5d .sx for the winter months .sx It is important in reading these figures to bear in mind the qualifications as to missed calls noted above .sx The median average weekly earnings of the latter group in the winter half-year ( October to March ) were 25s .sx , for the summer half-year 32s .sx The upper quartile was 28s .sx in the winter months , and 35s .sx in the summer months , while the lower quartile rose from 24s .sx in winter to 30s .sx in summer .sx The effect of seasonal changes can be seen in a six or seven shillings difference between the summer and winter figures , and of the levelling effect of the rotation system in the range between the upper and lower quartiles , which is 4s .sx only in the winter and 5s .sx in the summer .sx It can be fairly claimed that the rotation system equalized the opportunities .sx A consequence of the limitation of entry into the trade is that its members tend to be of a higher average age than in many other occupations in the port .sx According to the census of 1921 , the average age of all occupied males in the town was about thirty-eight , as compared with forty-seven in the case of " other dock labourers .sx " This higher average age is not due simply to methods of registration , for the Port Labour Committee had not been in operation long enough in 1921 , if it recruited its original tally holders on any ordinary interpretation of " habitual dockers , " to secure so pronounced a skewing of the age distribution .sx Much of the work is heavy and the opportunities for boys are therefore limited .sx It is clear that whereas random engagement at the dock gates with a large surplus of labour must have led to older men being gradually shouldered out of employment by younger ones , a restricted and stabilized entry with preferential treatment of registered men must in practice give them a longer life of average earning .sx The " ageing " of the docker , whether arising from the protection given to older men or otherwise , brings with it the possibility of the declining physical efficiency of the group as a whole , and of the necessity of securing a supply of younger men , or of arranging for the retirement of the older ones .sx Much of the success of a scheme of registration of this kind depends on the perfection of the administrative arrangements .sx Adequate arrangements must be made not only for compiling but for revising the register .sx It is not only a question of making .sx up wastage , of eliminating unsatisfactory cases , or scrutinizing cases with a poor or unsatisfactory work record in a routine manner , but of taking the opportunity to examine the total numbers of tallies in the light of any change in labour demand , whether due to trade depression or to other causes .sx A peculiar set of circumstances brought about in London an original registration of 61,000 , a much greater number than could possibly find work , and at successive revisions these were reduced to 52,000 in 1925 , 40,000 in 1928 , and 37,000 in 1930 .sx In Bristol the numbers were similarly reduced from 4,800 in 1921 to 2,800 in 1931 ; in Liverpool , from 35,000 in 1919 to 21,500 in 1931 .sx As indicated from the number of tallies given above , the total number has not been reduced in Southampton , for until the onset of the depression , its trade was growing .sx There is , however , a biennial review of the register .sx The size of the reserve needed is related to the number of separate " call stands , " their location and the mobility of labour between them .sx