The more interesting facts developed in the experiments upon quartz were published in Science during the year. A paper on the calcium silicates is nearly ready for the printer, and considerable progress can be reported upon a fundamental investigation of the scale of temperatures in terms of which all the work of the laboratory is exprest. The existing German scale extends only to 1,150° C., which is insufficient for effective work with the minerals. A gas thermometer was therefore constructed, and after several months of preliminary work it is possible to say that greater accuracy as well as greater range has been attained.

Members of the division have been engaged, also, in the study of finite elastic strains, as an incident to which a useful series of mathematical tables was prepared.

TOPOGRAPHIC BRANCH.

The organization of the topographic branch remained the same as it had been during the two immediately preceding years.

COOPERATION BY STATES.

Cooperative arrangements for topographic surveys were made with fourteen States. The governor of the State of Illinois allotted $10,000; the legislature of California appropriated $15,000; the director of the Kentucky Geological Survey allotted $5,000; the State Survey Commission of Maine, $3,200; the State geologist of Maryland, $2,500; the State geologist of Michigan, $2,000; the State engineer and surveyor of New York, $600; the commissioner of agriculture of North Carolina, $4,000; the governor of the Territory of Oklahoma, $5,000; the governor of Ohio, $23,800; the governor of Oregon, $2,500; the State Survey Commission of Pennsylvania, $14,000; the State geologist of West Virginia, $15,000; and $400 was allotted by the forestry commission of New Hampshire for a special sheet. Thus $103,000 was allotted by the States mentioned, in addition to the Federal appropriation for topographic work

SUMMARY OF RESULTS.

The following summary includes all small-scale topographic surveys made by the divisions of topography, including those of forest reserves, and by the division of Alaskan mineral resources:

Primary azimuth observations were made at two triangulation stations. Triangulation stations to the number of 328 were occupied or located and marked, and 3,261 miles of primary traverse were run. In the course of this work 51,430 square miles were covered by primary control.

The condition of topographic surveys to June 30, 1906, distinguished as to scale, etc., is shown on a general map of the United States, Pl. I,

and the detailed distribution of this work in the various States and Territories is shown on the accompanying maps, Pls. II-XXIII. On the latter are indicated by proper symbols the sheets published to June 30, 1906, the sheets in course of publication, and the areas surveyed during the field season of 1905 and drawn in map form in the office season of 1905-6. By appropriate symbols these maps also show areas in which precise or primary spirit levels have been run and unmapped areas which are controlled by primary triangulation or traverse or by astronomic positions.

As shown in the following table giving the details of topographic mapping and spirit leveling for the fiscal year, the total of new surveys was 36,605 square miles. The total area surveyed in the United States to date is 992,601 square miles, or about 32 per cent.

In addition, 3,179 square miles of revision or resurvey were completed by final topographic mapping in the eastern division and 1,01€ in the western division, over which preliminary reconnaissance surveying had been previously carried, thus making the total area of actual surveys for the season 40,800 square miles.

In connection with these surveys there were run 38,307 linear miles of spirit levels, of which 892 miles were precise, making the spirit leveling done since the authorization of this class of work by Congress, in 1896, amount to 196,371 miles. In addition, 327 miles of forestreserve boundary lines were run, 12 miles were retraced, and 15 miles of supplemental lines were run.

The total area covered by topographic surveys made in Alaska during the fiscal year 1905–6, as reported in detail on pages 25-26, was about 5,300 square miles, in the course of the mapping of which 191 miles of spirit levels were run and 26 permanent bench marks were established.

Present condition of topographic surveys of the United States, and new areas surveyed in

Present condition of topographic surveys of the United States, and new areas surveyed in

1905-6-Continued.

During the season topographic surveying was carried on by 67 parties working in 26 States, namely, Alabama, Arkansas, Georgia, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maine, Maryland, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, New York, North Carolina, North Dakota, Ohio, Pennsylvania, South Carolina, Vermont, Virginia, West Virginia, and Wisconsin. The survey of 49 new quadrangles and the resurvey or revision of 11 reconnaissance sheets were completed. In addition, 60 new quadrangles were partly surveyed and 8 were partly resurveyed. The total new area mapped was 14,863 square miles, of which 3,076 square miles were for publication on the scale of 1:125,000 and 11,787 square miles were for publication on the scale of 1:62,500. There were resurveyed or revised 1,296 square miles on the publication scale of 1:125,000 and 1,883 square miles on the publication scale of 1:62,500.