In preparing to secure data for 1906 copies were made of the data for 1905, obtained in the preceding year. These copies were placed in the hands of the special agents of the Bureau, who visited the establishments and secured 1906 data, and whenever any doubt arose verified or, if necessary, revised the data for 1905. The agents were also instructed to secure data from a few additional establishments, in order to secure a better representation for the several industries and localities covered. Where data were obtained from additional establishments, figures were taken for both 1905 and 1906. All data for the two years, 1905 and 1906, shown in this article, therefore, are from identical establishments, and may properly be compared. During the course of the field work it was also found that a few of the establishments heretofore covered had gone out of business. With some establishments added and others discontinued it will be seen that the establishments from which data were secured for this Bulletin differ to some extent from the establishments shown in preceding reports on this subject.

With a change in the establishments reporting, some difference necessarily must be expected between the average hours of labor and average wages per hour shown for the year 1905 in Bulletin 65 and in this Bulletin. Two groups of establishments, even though many establishments are common to both groups, can not be expected to show exactly the same averages. Neither statement may be absolutely exact for the occupation, yet if each group embraces a considerable number of establishments the average rates found may be accepted as representing approximately the average rate in the occupation considered. The average based on the larger number of establishments probably would be the more nearly representative. To secure the exact average rate of wages and hours of labor for the United States it would be necessary to take a complete wage census of the United States, and, as previously stated, such a task is so great as to be practically impossible.

To measure with exactness the movement in wages and hours of labor it would not be proper to compare the average for one group of establishments for 1905 with the average for a different group of establishments for 1906, nor in practically the same establishments if any change or substitution of establishments whatever has been made. Comparison can be made accurately only when the data. compared are obtained from identical establishments. As one of the principal objects of this series of reports is to measure the change from year to year as accurately as possible, increases and decreases from year to year are computed only on data taken from identical establishments.

A statement of rates of wages is incomplete without an accompanying statement as to hours of labor, as both factors must be known to determine the earnings on full time per week, month, or year. The average hours of labor are given in this report in connection with the average rates of wages. The average hours of labor shown are true averages, computed in the same manner as the average wages per hour.

The hours of labor given in this report represent the regular full time hours of the occupation-that is, the time that the employees as a class were engaged in work. No account has been taken of time lost by individual employees because of a desire not to work, of bad weather, or of slack work. It is no part of the purpose of this article to measure the amount of unemployment, and it must not be inferred that all employees engaged in the establishments reported in this article worked full time. To ascertain the time lost in a year by the employees remaining in the establishments a year would be an almost insuperable task, while to ascertain with any accuracy the time lost by employees who have moved from one establishment to another would be practically impossible.

The sex of the employees for whom data are presented is shown for each occupation. In many occupations few, if any, females are employed, and in other occupations few, if any, males are employed. In such occupations data are given for one sex only. In a number of occupations, however, in which many persons of both sexes are employed, data are presented for both sexes, that the occupation may be properly represented.

EXPLANATION OF TABLES.

The tabular matter of this article relating to wages and hours of labor is set forth in five general tables, and a number of short tables shown in the text explaining and summarizing such general tables. The five general tables are entitled:

TABLE I.-Average wages and hours of labor, 1905 and 1906, by occupations and geographical divisions.

TABLE II.-Relative wages and hours of labor, 1890 to 1906, by occupations.

TABLE III.-Relative wages and hours of labor, 1890 to 1906, by industries.

TABLE IV.-Average wages and hours of labor, 1905 and 1906, in selected occupations, by cities.

TABLE V.-Average wages and hours of labor, 1905 and 1906, in selected occupations, by States.

Table 1.-Average wages and hours of labor, 1905 and 1906, by occupations and geographical divisions (pp. 26 to 60).—This table presents the data secured for each occupation in each industry, by geographical divisions and for the United States. The classification of the States into geographical divisions is as follows:

Were the figures shown in Table I not used to measure the trend from one year to another the decimals of the hour and of the cent might well be dropped from the table. But while a slight difference is not material in itself, so far as it affects a representative number, it is very material when indicating a trend or movement upward or downward in hours or wages. As stated before, the establishments that reported the data for 1905 shown in this Bulletin are the same as those that reported the data for 1906; hence there is opportunity for an exact comparison between the number of employees, the hours of labor, and the wages per hour in 1905 and in 1906, and the figures may safely be used to indicate and measure the trend or movement upward or downward of employees, hours, and wages in the several occupations and localities covered.

In Table I (p. 26) the second column shows the number of establishments from which data were secured for both 1905 and 1906. The next two columns show the number of persons employed in 1905 and 1906, respectively, in the establishments from which data were

secured. The two columns following show the average number of hours worked per week in each of the two years in these establishments, while the last two columns on the page show the average wages per hour in each of the two years covered. The averages shown are true arithmetical averages. They are obtained by finding the aggregate hours worked per week by all workers and the aggregate earnings per hour, and dividing these aggregates by the total number of persons considered.

An illustration will assist in explaining the table. The figures for bricklayers in the building trades are presented on page 29. Data for this occupation were secured for both 1905 and 1906 from 73 establishments in the North Atlantic division. In these establishments 1,951 persons were employed in 1905, and 2,035 persons in 1906, an increase of 84 persons. The average hours of work per week of these employees were 45.76 in 1905 and 45.74 in 1906, a reduction of 0.02 hour per week. In 1905 the average wages per hour were $0.5833 and in 1906 $0.6091, showing in this occupation an increase in wages of $0.0258 per hour in the North Atlantic division.

Table II.-Relative wages and hours of labor, 1890 to 1906, by occupations (pp. 61 to 125).—In Table I actual or concrete numbers only are shown, and such figures relate only to the two years 1905 and 1906. No attempt has been made to join the actual numbers expressing employees, hours, and wages for 1906 to the actual numbers for the period from 1890 to 1905, shown in the Nineteenth Annual Report and in Bulletins 59 and 65. On page 17 an explanation has been given why such a combination can not be made.

The figures presented in Table II are relative numbers or, in other words, a series of percentages. Relative numbers serve a double purpose-first, they present to the mind of the reader more clearly than the actual or concrete numbers the measure of difference between the data for a series of years, and, second, by their use combinations are made possible that are not possible with concrete numbers.

In Table II all figures for the years from 1890 to 1903 are from the Nineteenth Annual Report, all figures for 1904 are from Bulletin 59, and all figures for 1905 from Bulletin 65; the figures for 1906 were obtained by computation. An illustration will best explain the method of computing relative numbers and the method of attaching one series of data to another by use of the relative number. Data were secured for the Nineteenth Annual Report from 212 establishments in the United States employing bricklayers in the building trades for each year from 1890 to 1903. The following table shows the number of persons employed each year and the relative numbers computed therefrom.

ACTUAL AND RELATIVE NUMBER OF BRICKLAYERS EMPLOYED IN 212 BUILDING ESTABLISHMENTS, 1890 TO 1903.

[From the Nineteenth Annual Report. Average number for 1890-1899-100.0.]

The average number of persons employed for the ten years from 1890 to 1899 was first computed. This average number, 4,355, was adopted as a base or standard for comparison. All comparisons might be made with 1890 or any other year, but, owing to the fact that the conditions in any one year might have been abnormal, it was determined to take as a base for comparison, or 100.0, not any one year, but the average for the ten years 1890 to 1899. The number of employees in the 212 establishments in 1890 was 4,422, which was found by computation to be 101.5 per cent of 4,355, the base number. Therefore the relative number of employees in 1890 was 101.5. The relative number was computed in like manner for each succeeding year. In looking down the two columns the reader will see that the relative numbers convey a clearer idea of the extent of the change in the number of employees from year to year in the establishments reporting than do the actual numbers themselves.

Data for bricklayers were secured for Bulletin 59 from 229 establishments for 1903 and 1904. As these establishments differed to some extent from those shown for the years 1890 to 1903 in the Nineteenth Annual Report, direct comparison can not properly be made between the number of employees in 1904 shown in Bulletin 59 and the number in 1903 reported from the 212 establishments in the Nineteenth Annual Report. For the establishments covered in Bulletin 59, however, comparison could be made between the number of persons employed in the two years as shown in Table I of that report. In the 229 establishments 4,853 bricklayers were employed in 1903 and 4,644 in 1904. The number employed in 1904 was 95.69 per cent of the number employed in 1903. As shown in the above text table, the relative number of employees in 1903 was 116.2 as