therefore, erected a three-story structure in the entering angle of his residence, corner of Capitol and Market streets, Iowa City, and fronting north. The two upper stories and the flat roof or terrace of this structure [see cut] were set apart for the use of the service, and have been so occupied since September, 1879. On the roof or terrace of this building are the instruments which require full exposure, such as wind-vanes, wind force plate, Robinson's anemometer, insulation thermometer, radiation thermometer, rain-gauge, evaporimeter, and the like; also a flag-staff for the display of flag and lantern signals. Besides, this terrace is the place for observation of sun-spots, and of all general meteorological phenomena, as it furnishes a fine view of the entire landscape and a free view of the sky, the building standing near the edge of the bluff east of the Iowa river.

The room immediately below this terrace is the meteorological observatory proper. The windows furnish a fine view of the sky in all directions, and an arrow on the ceiling marks the direction of the wind. Standard mercurial barometers and aneroids give the pressure of the air, while temperature and humidity are observed on a full set of standard thermometers, a psychrometer, and an improved hair-hygrometer in the case attached to the east window of the north wall. Here are also many additional instruments, and meteorological collections have been begun, such wind-worn and polished rocks, specimens of wood showing the effects of as tornadoes and of lightning, and especially a fine collection of meteorites from all parts of the globe.

THE FIRST LUSTRUM OF THE SERVICE, 1876-80.

The first International Congress of Meterologists introduced the lustrum or period of five years; beginning with the first and sixth year of each decennial period. Our Service, having begun observation on Oct. 1, 1875, has therefore completed one such period, from Jan. 1, 1876, till Dec. 31, 1880.

RAIN-FALL IN IOWA.

The only results fully reduced from the observations of the Volunteer Observers of the Service and covering the entire lustrum 1876-80, are those relating to the rain-fall. The following table indicates the fullness of the material used:

Total number of monthly reports seceived, 4,671, including 195 recieved

during the first three months of the service, from October to December, 1875. The total number of rain-fall measurements made is 26,082. Hence the average rain frequency per month has been 5.5 during the lustrum for any one station. More accurately the rain frexuency during the year 1878 to 1880 has been 6.2 per month for each station, or one day in five has been a rain-day.

From the tables it appears that the mean annual rain-fall of Iowa has diminished from 1876 to 1879, and is now increasing; that the diversity of distribution was greatest when the mean annual rain-fall was greatest, increasing and diminishing with the same.

For each month and for each year a rain-fall map is constructed, constituting now a large atlas of eighty-four maps. Many additional rain-fall maps are drawn, for decades, special storms, seasons and the like.

RAIN-FALL AND TIMBER.

The rain-fall maps constructed for each year, and for the lustrum 187680, show conclusively that the amount of rain-fall in Iowa is largely influenced by the distribution of timber, the annual rain-fall increasing with the amount of timber or foliage in the different portions of the State. The amount of rain-fall in any large territory like Iowa, occupying a considerable portion of a continent, is undoubtedly first of all determined by its position in such continent. In the case of our own State, the rainfall is primarily conditioned by our position in the great Mississippi Valley, which owes its relatively high rain-fall to the southerly winds blowing from the gulf.

The distribution of this rain-fall, expressed in the form of the lines of equal rain-fall is, however, as matter of fact, in Iowa, remarkably specialized: and this same peculiar form of curves is repeated in the lines representing the distribution of timber within our State. As now, finally, neither elevation nor any other physical element in our State is found to correspond, the conclusion appears irresistible, that the distribution of rainfall over the territory of our State is closely related to the disibuction of timber in the same. It may, therefore, be asserted as fairly established by the five years' work of our service, that in the planting of timber we possess a means to increase the amount of rain-fall for a given region.

The following rain map is a pictographic exhibit of the practical conclusions wrought out by the five years' work of Dr. Hinrichs and his

co-observers:

FURNISHED

MONTHLY

REPORTS REGULARLY DURING THE FIRST LUSTRUM OF THE SERVICE.

Grand Junction, E. J. Couch and Geo. Cough, Farmers.

McGregor, Hon. Frank Larrabee and Miss Rachel Larrabee.

Waukon,

Francis H. Robbins, Druggist.

Gregory Marshall, Farmer.

Gershom H. Hill, M. D.

D. W. Crouse, M. D.

Hon. Jacob K. Wagner, M. D.
Mrs. May U. Remley.

M. M. Moulton, City Marshal.
Prof. Thomas Myrick Irish.
A. B. Bowen, M. D.

Cresco,

Clermont,

Miss Augusta Larrabee.

Independence,

Waterloo,

Blairstown,

Anamosa,

Monticello,

Dubuque,

Maquoketa,

Davenport,

Tipton,

Muscatine,

Iowa City,

Amana,

Oskaloosa,

Fairfield,

Brookville,

Crawfordsville,

Mt. Pleasant,

Denmark,

Burlington,

Prof. D. S. Sheldon and Miss Sarah G. Foote.
H. H. Maynard, M. D., and Thos. Rigg, Druggist.
Prof. Finley M. Witter.

Hon. J. D. Miles and Theo. W. Bennett, M. D.
Miss Anna Hinrichs.

Conrad Schadt, Druggist.

H. C. Huntsman, M., D.
Geo. D. Clarke, Druggist.
Curtis Houghton, Farmer.

M. Riordon, M. D., and Hiram N. Bassett, M. D.
Col. Gustavus B. Brackett, Horticulturist.

Dr. Charles Wachsmuth, Palæontologist.

Sherman Twp., Jasper county, Edwin T. Preston, Farmer. Grant Twp., Union county, Capt. Chas. S. Stryker, Farmer. The work done by the observers named is doubly valuable because it has been continuous, Even where a change became necessary, the observers named had sufficient interest in their work to secure its continuation by a competent person. As this work is altogether gratuitous and voluntary, it will be seen that it was no small labor done for the public. benefit; and the people who did it are worthy of perpetual honor and gratitude, for such reports are of no value unless kept up faithfully for a series of years.

IOWA CITY WEATHER REPORT.

The following local report for Iowa City is also by Dr. Hinricks:

TWENTY YEARS' NORMALS OF TEMPERATURE AND RAIN-FALL.

For Iowa City we have the record of the observations of Professor T. S. Parvin, begun in 1861, and our own observations, begun in 1871. The observations of Professor T. 8. Parvin have been copied from his original journals for the years 1861 to 1870, and properly reduced. The same has been done for my own series of observations, for 1871 to 1880. The two series combined give, by the so-called secondary means, the values given below for each decade of each month, covering this period of twenty years, 1861 to 1880:

NORMALS BY DECADES AND MONTHS, FOR THE CENTRAL STATION, I. W. 8.,

For Twenty Years Observations, at Iowa City, Iowa, 1861-80.

These temperature normals are the results of 30,000 observations, of which about 11,000 belong to Parvin's series, the other 19,000 to my own. I have determined the mean temperature of every other day of the year from the above, the first thoroughly reduced and nearly uniform series of twenty years' observations for any one place in the State.

These values are of great importance for the determination of the character of any day, as to its being hot or cold, and how much above or below normal it may be. The following table gives the normal mean temperature for every odd date of the year; the values for the days of even date are obtained by interpolation at sight. Thus: January 16th has a normal mean temperature of 19.1 degrees.

NORMAL MEAN TEMPERATURE FOR EACH DAY OF THE YEAR,
Determined from Twenty Years' Observations, at Iowa City, Iowa

DATE.

Jan. Feb. Mar. April May. June. July. Aug. Sept. Oct. Nov. Dec.

Persons who may wish to investigate this Weather Service matter still further, can obtain sundry printed reports on it by applying to Dr. Hinricks. The observations throughout the state are compiled at the Central Station and printed by the State Printer in monthly bulletins; and no one can realize or fairly comprehend the nature, extent and real value of the work being done without examining a series of these well edited and neatly printed bulletins.