and towns supplied from the Metropolitan Works was 4,334, or 77 more than during the previous year. The number of meters set in the different cities and towns, with the percentage of the total number of services metered at the end of the year, was as follows:

The number of meters now in use in the several cities and towns is shown in Appendix No. 2, Table No. 38.

QUALITY OF THE WATER.

The quality of the water supplied to the Metropolitan District has continued good throughout the year. The number of microscopic organisms has been smaller than during the two previous years and the color substantially the same.

Samples of the water have been collected monthly from 24 points, and semimonthly from 5 points on the works, and sent to the State Board of Health for chemical analysis. Samples of water have also been collected weekly at 35 points and biweekly at 8 points, and examined microscopically and for color, odor, taste and turbidity in the biological laboratory of the Metropolitan Water and Sewerage Board.

The following table gives a comparison of the average results of the examinations of water from a tap in Boston for the years 1900 to 1907, inclusive:

NOTE. - Chemical analyses are in parts per 100,000, organisms and amorphous matter in standard units per cubic centimeter, and bacteria in number per cubic centimeter. The standard unit has an area of 400 square microns, and by its use the number of diatomaceæ are decreased, and the number of chlorophyceæ and cyanophyceæ are very much increased, as compared with the number of organisms.

1 Platinum standard.

In the biological laboratory there have been made 2,624 microscopical, 1,212 biological and 24 chemical examinations of water collected at various points upon the works. Of the microscopical examinations, 1,996 were of the regular weekly and biweekly samples, and 628 were special examinations.

The bacteriological work consisted of routine weekly examinations, monthly examinations of the main feeders of the Sudbury Reservoir, of Framingham Reservoir No. 3 and of Lake Cochituate, and monthly tests of the efficiency of the Pegan Brook, Marlborough Brook and Sterling filter-beds.

The organisms in the Wachusett Reservoir have been small in number and generally unobjectionable in character. A growth of Uroglena, which caused an objectionable taste and odor, was present in the water near the surface of the reservoir, in the vicinity of the dam, for about two weeks in June, but the water at a greater depth was not affected. The examinations made by the State Board of Health show that the color of the water and the quantities of both free and albuminoid ammonia were lower than during the preceding

year.

The water in the Sudbury Reservoir, and in Framingham Reservoir No. 3, is largely supplied from the Wachusett Reservoir, and

like the water in that reservoir has been of better quality than in previous years. The number of organisms present in the water of both these reservoirs was less than for any year since 1904. Two growths of Uroglena developed in the Sudbury Reservoir, one in June and the other in November, the latter continuing to the end of the year, but the number of organisms present was not sufficient to cause objectionable taste and odor in the water delivered to the Metropolitan District.

In Lake Cochituate the number of organisms was larger than in any other source, with the exception of Whitehall Reservoir. Objectionable organisms were present nearly all of the time, and for about one-third of the year in sufficient numbers to make the water undesirable for use.

The organisms in the Ashland and Hopkinton reservoirs have been few in number and unobjectionable in character.

The water in the distributing reservoirs has generally been free from large numbers of organisms.

From May 27 to June 18 there was a large growth of Uroglena in the Waban Hill Reservoir, and growths of the same organism in the Mystic Reservoir made it necessary to shut that reservoir off from the pipe system from April 10 to 18.

SANITARY INSPECTION.

The sanitary inspection of the watersheds has been continued under the immediate supervision of William W. Locke, C.E., Sanitary Inspector.

On the Wachusett watershed 2 cases of typhoid fever were reported in Holden, 2 in Princeton, 1 in Sterling and 1 case of dysentery in Holden, as compared with 11 cases of typhoid fever during the previous year.

On the Sudbury and Cochituate watersheds 11 cases of typhoid fever were reported in Marlborough, 7 in Natick, 7 in South Framingham and 5 in Westborough, a total of 30, as compared with 44 during the year 1906.

There were no epidemics, and in 18 cases the patients resided in houses connected with the public sewers which discharge outside the watershed.

The sanitary conditions on the Wachusett watershed have been improved during the year by the demolition of 10 buildings on prop

erty belonging to the Board, by the construction of 3 cesspools and 1 cemented brick privy vault in Sterling, by the completion of 2 acres of filter-beds, constructed for the purpose of purifying the water of the brook which receives unsanitary drainage from about 225 acres in Sterling, including the thickly settled portion of the town, and by the construction of 4 small sand filter-beds for purifying the drainage from 5 dwellings near the Sterling camp grounds.

On the Sudbury watershed 94 old and 7 new premises were connected with the public sewers which convey the drainage outside the watershed; 45 of these premises are in Marlborough, 52 in Westborough and 4 in Framingham.

On the Cochituate watershed 69 old and 19 new premises were connected with the public sewers; 41 of these are in Framingham and 47 in Natick.

At the request of the Board tight floors have been laid by the railroad companies on the New York, New Haven & Hartford Railroad bridge crossing Framingham Reservoir No. 3, and on the Boston & Albany Railroad bridge over the Sudbury River just above Framingham No. 2, for the purpose of preventing direct pollution of the water from passing trains.

Considerable time has been devoted to inspection to prevent the pollution of the water supply by large gangs of men engaged in building and repairing State highways in Boylston, West Boylston and Holden, in widening and reconstructing Worcester Street between Framingham and Fayville, in widening the road-bed of the Boston & Albany Railroad between Natick and South Framingham, and in laying water pipes for the Westborough Insane Hospital in Crane Swamp.

A summary of the work of sanitary inspection for the year 1907 is given in the following four tables. The first table shows for the Wachusett watershed the number of premises inspected, the classification of cases inspected, and the condition of the premises at the end of the year; the second table gives the corresponding information for the Sudbury and Cochituate watersheds; the third table shows the improvements effected on the Wachusett watershed; and the fourth table the improvements effected on the Sudbury and Cochituate watersheds.

The headings of these tables are easily understood, except in a few instances under the heading "Premises Vacant" are included all

cases which at present furnish no objectionable drainage, but which might furnish such drainage if the premises were occupied; under the heading "Unsatisfactory" are included all cases where there may be, under the most unfavorable conditions, wash from privies or direct sink drainage, all suspected cases, and all cases of manufacturing wastes entering feeders, even though there may be some attempt at previous purification.

In the third and fourth tables no cases are entered as remedied unless complete sewer connections have been made, or all probability of future contamination has been removed; and no cases are entered as partly remedied except where positive improvement in the sanitary condition has been effected.

Summary of Sanitary Inspections on the Wachusett Watershed in 1907.

1 On some premises there are 2 or more cases.

2 Not including 204 summer cottages located near the Waushacum Lakes.