Box 4, Folder 4: Typewritten Letters 1871-1875

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1872.

Smithsonian Institution Washington Feb. 7th, 1872.

Dr. I.A. Lapham,

Dear Sir,-

We regret to learn of your withdrawal from the active duties of meteorological observer to this Institution for the city of Milwaukee, but trust that you will not allow your interest in the science you have so long and faithfully labored to advantage, to abate in the least.

It will always give us pleasure to hear from you as well as to render you any services in our power.

Very truly yours,

Joseph Henry Sec'y.

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Meteorological Notes and Memoranda.

In or about the year 1793 a very violent hurricane passed over Pennsylvania leaving a wind fall extending through Elk and several neighboring counties. In October 1864 I examined the ground near Hemlock station on the Phila, and Erie Ry. in Elk Co.; found remains of logs, hillocks formed by turned up roots; and by the growth of hard wood that had taken the place of the conifers along the course of the storm, its course could be traced across the mountains of this broken country.

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At Woodland Wis. in 1857 in August, cars were turned over and the whole town demolished except two houses. Hotel moved 18 inches. Great noise heard at Hustisford. A mile north of Hustisford a water spout across Rock river, [here a lake.]

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1872.

Largest trees blown down in a narrow path. Jan. 1st 1868 another storm at same place, blow lasted but a few moments.

Oconomowoc May 31st. 1851--Great rain 9 to 10 A.M. at Summit. Reported by E.W. Spencer.

A tornado passed over Summit corners July 3rd, 1853 at 3 P.M. Began at south part of Silver Lake and ended near east end of Oconomowoc Lake, cut through woods south of Soft Water lake (these woods all cleared off before 1872) a path two or three rods wide; lifted roofs from houses and barns. Hotel at the corner burned. Small house moved across the road. East half of B.R. Hinkley's barn destroyed--a stack of timber lifted and carried some distance, [&c. &c.].

Tornado in Jefferson Co. Wis. May 31 1851, also at St. Louis the same day. Trees blown down, houses unroofed for four miles on the plank road. The clouds came in contact over the farm of Abel Nutting in Farmington and prostrated about 50 acres of beautiful timber.

The same day a tornado near 2nd lake Dane Co. (6 miles from Madison). A gentleman standing at his door observed "far above the tops of the forest trees a dark column of leaves and branches whirling round with great rapidity and the forest bent before it like reeds." The noise and confusion defied all description. A track covering more than 100 acres was stripped bare.*** the ground looked as if it had been harrowed.*** A girl thirteen years of age carried over the tops of trees clinging to a feather bed and landed without injury.

Oshkosh July 8th, 1861, Sunday night buildings unroofed &c. shipping injured, storm from S.W.

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1302 -1462-

1872.

Milwaukee Wis. May 1872.

To Gen'l A.J. Meyer,

Chief Signal Officer,

Dear Sir,--

It is the duty of surveyors of the public lands of the United States among other things to note the "wind-falls" over which their lines occasionally run, much to their inconvenience; and from these notes some very important information can be derived in regard to the tornadoes that have swept over the land, their frequency, their direction, and the length and breadth of country over which they pass with destructive force.

The government lands are first surveyed or divided into squares of six miles each way, called townships, which are subsequently sub-divided into sections of one mile square.

The exterior lines of every square mile of territory are thus traced and measured. While running these township and sectional lines the survey or notes when he reaches and when he leaves a windfall, and we thus have accurately recorded the exact position extent and direction of the track of all the tornadoes that have passed over the country within a space of time during which the trunks of trees remain upon the ground un-decayed. Of course it is only through the wooded districts that these windfalls are to be found.

Few traces of the ravages of a tornado are left on the open or prairie country, while in their original, natural condition.

To render this knowledge available to the Signal Service I have carefully examined all the plats of public surveys within this state, and represent the result upon the accompanying map, a detailed examination of which shows that about three hundred and

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1872.

sixty wind-falls were encountered. It will be seen they came from all directions, from south by west to north. A large number were of so little extent that their direction is not indicated with certainty, only about fifty extend across so many of the section lines as to show their proper course.

Of these thirty eight were from points south of west with a mean direction of S 54 degrees W. and fifteen were from points north of west, with a mean of N 54 degrees W. These were wind-falls whose direction was from south and south-west. Twenty nine from between South-west and west; thirteen between west and north-west; and two directly south; three from directly west and one from the north.***

If we examined the records of meteorological observations made on the days when these several tornados occurred, whether in their immediate vicinity or at considerable distance, we shall find the barometer low, indicating diminished pressure of the atmosphere and the thermometer high, showing unusual temperature; heavy rain also and high winds are usually noted.

The facts brought forward give support directly or by fair inference, to the following conclusions;

Tornados are cyclones having both a whirling and progressive motion; reduced to a small size, but having excessive force and power.

They occur when the barometer is low, the thermometer high and the air usually calm.

They have their origin in the upper air, forming a cloud from which they descend in the form of a dense black column to the ground.

They are identical with the water spout.

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1872 [not 1873].

The gyratory motion of the air forming or surrounding the column is spirally upwards carrying with it quite heavy bodies which are thrown off by centrifugal force.

They move over the country from all points west of the meridian or from north by west to south.

They are accompanied by a sudden and very considerable diminution of temperature, producing clouds, rain and hail, they also exhibit extraordinary electrical phenomena.

While the tornado is raging with destructive violence along a narrow and well defined track, the atmosphere in the immediate vicinity remains comparatively undisturbed.

They do not always reach the ground and are often interrupted in their course along the surface.

They extend from a mile or so in length to fifty miles or more, and in breadth of destructive force they vary from a few yards to a mile or more.

They occur in this latitude from May to October inclusive, and in the night as well as the day time.

They are accompanied by loud and unusual noises, often heard at a great distance.

Two or more may be moving in nearly parallel lines; they may approach and unite into one; or one may be separated into two.

Besides the effect of the direct pressure of the wind moving with great velocity in destroying buildings &c. the rarified air within the column of the tornado causes a lifting or bursting of houses &c. by the elastic force of the dense air within them.

They are supposed to have a tendency to pass a second or third time over the same, or nearly the same track.

Very respectfully,

I.A. Lapham Asst. to the Chief Signal Officer.