Having made these general statements, we may now examine more particularly the bearings of objects prostrated by the wind. The following table contains the bearings of a survey across the path of the tornado, 1 mile S. West of Brandon, commencing on the right. The plot of these bearings will be found in the

left part of Section I.

Course of the storm,

N. 561° E.

N. 561° E.

N. 45° E.

N. 561° E.

N. 224° E.

N. 45° E.

6. A tree,

N. 22° E.

11. A fence,

12. A tree,

N. 6° W. This was near the middle of the track.
N. 111° W.

13. A hickory, diagram (23) N. 45° W. The top after falling broken off and turned

14. Three oaks,

15. Trees in orchard,

16. Roof of Baxter's barn,

N. 45° E.
E. 10° S.
E. 45° S.

round to the East.
Near the hickory, but much smaller.

A fence at this point, running east from Baxter's barn, was found to have been thrown along the western half towards the south, while the eastern half was prostrated northerly. This prostration of the halves of the fence in opposite directions, together with other peculiarities in the position of objects, induced the writer to believe that a secondary or double whirl existed at this place, the one on the right being in advance of the other.

The hickory was thrown down (Section 4, No. 2) across a ravine, and afterwards half of the tree, including the top, was turned round towards the east. The same current which produced this effect, prostrated three small oaks (3). The shingles from Baxter's barn (1) were first carried southeast, and then strewed for fifty rods in a curved line gradually bending in towards the course of the storm. The curved arrows from the barn correctly represent the arrangement of the shingles. Trees in an orchard near by were thrown down E. 10° S., coinciding in direction with the fragments from the barn.

The central whirl of the storm passing over the hickory and oaks, might account for their position, but not for that of the fence. The evidence from the latter of a secondary whirl, was as clear and explicit as well could be. Had the rails been removed by hand and laid on opposite sides, the result could not have been more regular. A secondary whirl about 60 rods in diameter, lagging a little behind the more extended one on the right, seems undeniable from the facts in the case.

To what extent this may have disturbed the general action, it is impossible to say. Its existence, if admitted, did not however

continue long, for all trace of it is lost in the forest one-fourth of a mile east of Brandon.

We will now examine briefly the action of the tornado at Brandon. The right hand part of this storm seems to have slid over that division of the town, merely prostrating fences and unroofing some small buildings. Its destructive effects were felt mainly in the middle and left hand portions.

A careful examination on the right of the path through the town, was not made; the approach of night cut it short: and the subsequent observations were given to a part of the track farther east. Section I represents that portion of the town most severely visited; and the arrows represent the direction in which objects. were prostrated. The cluster of arrows (18) mark the position of trees in an orchard. Their direction was from N. to N. 10 W. Casting the eye from this point along the track of the storm, the buildings 7, 8, 12, 14, 15, 16, give the same general result. Combining them we obtain the mean N. 5° W. If we take another section farther to the left, commencing with the brick church (6) and extending nearly to Dr. Wheaton's house (5), we obtain a mean result of N. 15° 5' W. From this estimate a tree (20) and the church (9) are rejected. No. 20 was an apple tree which had been twisted more than 45° after falling. The roof of the church was torn to fragments and scattered between N. E. and N. W. The direction in which the wind struck the church, can be made out with sufficient accuracy from other data. 1st, The south gable end was crushed in, and 2d, A bier was lifted from the grave yard, carried across the street along the line of the dotted arrow, and set down in the church yard.

The remaining objects on the left including Dr. Wheaton's house and barn, and the trees near the creek give a bearing of N. 33° 45′ W. From this 21 was rejected. It was a small oak, broken partly off, and turned round 90°. No. 22 was a limb from a tree carried S. 10° E.; supposed to be due to the reverse action of the storm. In the tabular view of these bearings given below, in order to fill it out for the right of the track, for which no materials existed in Brandon, the first three are interpolated from a survey farther west.

The bearings from this table are remarkable; and if the reader will construct a curve to suit them, he will find a singular correspondence with the cycloids which were planned with special reference to Sections II and III.

To these sections we will now turn. Section II represents a survey across the path of the storm, one-fourth mile east of Brandon, where it first struck the forest. The distances from bearing to bearing were not measured with a chain: it would have been impossible to use one in the midst of such a mass of fallen timber. They were determined, as nearly as could be, by the eye. On the right of the dotted line, the number of bearings might have been increased to any extent, as the ground was covered with fallen trees. The largest and straightest trees were selected. Those which were partially decayed or which had been thrown down by others were rejected. The arrows do not in every instance represent the relative distances of the trees from each other; in many cases they lie side by side in contact. On the left of the dotted line, they are sometimes placed nearer in the plot than was actually their position. The direction is accurately given. The arrows with cross-bars point out trees which lay across others. The prostrations appear to have been made almost entirely by the front of the tornado, with the exception of the left hand portion of the path, where the reverse action was frequently the most violent. This front action rendered the position of the trees more symmetrical, and the mode of action of the wind easier of solution. Objects thrown down at the first stroke of the current would accurately represent a tangent to the curve at that point, whatever the nature of the curve might be. As the trees which fell above others, must have been struck down after a part of the storm had passed, and cannot therefore exhibit the front action, they are on this account either rejected in obtaining the mean of the bearings, or included with others in the reverse action. The parallel lines were drawn to aid the eye in grouping the trees. Where the trees lie across them, they are included in that interval whose bearings most nearly correspond.

A tabular view of Section II, one-fourth | A tabular view of Section III, six miles mile east of Brandon,- mile wide. east of Brandon,- 4 mile wide.

The curtate cycloids were constructed to represent approximately these tabular views. The radius of the generating circle. is to that which describes the curve as 1; 2. The blanks in the

loop of either section could be supplied by interpolation from the other.

The barred arrows on the left of the loop in Section III designate trees which, though lying side by side with those on the opposite part of the same loop, yet rested with their limbs above the latter. The barred arrow in Section II which lies at the intersection of the curve was resting upon six large trees. An involute converging rapidly towards the centre might answer tolerably well the conditions of Section II, but it fails entirely when applied to Section III.

The involute action does not seem to have been distinctly marked. While passing rapidly over another part of the track, the bearings of scattering trees which were taken afforded more significant indications of the involute form near the axis. The relative distances in the latter case were not noted with sufficient accuracy to justify a projection.

The data thus far given are believed to be sufficient to enable the reader to form an intelligent opinion of the mode of action of this tornado. A few additional observations may afford some further aid.

1st. The space between the dotted line and the right hand border of the storm includes the path of most destructive violence. Within this limit almost every tree was prostrated or broken. This limit was clearly defined, especially on the left where the tornado first encountered the forest; but after plunging into it for some distance, its action became more obscure, and less symmetrical.

2d. On the left of the dotted line the force was much less violent, but trees enough were prostrated to determine the direction. of the wind.

3d. No case was found of an object on the right thrown inward more than 110 or 12°. The mass of the trees on the right border lay parallel with the course of the storm.

4th. Along the dotted line, the trees generally lay N. 23° W.; making an angle of 791° with the general course of the storm. 5. Very few cases were observed of objects in the centre thrown forward in the direction of the path.

6th. There was no distinct case of the outward explosive action in buildings. The ascending current was, notwithstanding, very violent, for large objects were raised and transported several

miles.

7th. Persons just outside of the path describe the storm as a column of vapor or smoke, whirling in indescribable confusion, accompanied with a deafening roar, so that the thunder, if any, was undistinguishable amid the general din and confusion.

8th. The atmosphere on the borders of the track appeared to suffer but little disturbance from the passage of the storm; and no current could be observed setting in towards it.

9th. There was scarcely any hail, but torrents of rain followed the tornado, equally, and perhaps, more abundant outside of the track than within it.

10th. The temperature sunk so rapidly that the next and succeeding days became marked as among the coldest in the month.

Rate of Progress.

Great discrepancy existed between different observers in reference to the progress of the storm. The estimated time of its passage over any one place varied from one-half to one and a half minutes. Mr. Coleman stated that he saw the whirling mass coming when three-fourths of a mile distant, and that he took scarcely five steps before he was struck down. If we take one minute as the time of its passage over any point, and three-fourths of a mile as the diameter of the storm, we obtain a velocity of 45 miles per hour.

I have not been able to obtain the barometric minima along the track of this extended S. West current; but if the lowest depression of the atmospheric wave passed near Little Rock, Arkansas, at noon on the 19th, then to have reached Oxford, Ohio, at 12 P. M. on the 20th, would have required a velocity of nearly 29 miles per hour. My own opinion is that the first estimate is nearer the truth. The clouds during the forenoon of the 20th, flew past with a velocity which attracted special attention.*

In reference to the velocity of rotation an approximate estimate only can be reached. If the ratio of the progressive and rotary velocities adopted in the construction of the cycloid be correct, and 40 miles per hour be taken as the rate of progress, then the velocity of the wind on the right would have been 120 miles per hour. This velocity would be increased, especially near the axis, by the involute form of the curve; but to what extent this operated cannot be stated.

Another mode of estimating the force of the wind may be adopted. Among the oaks previously named as standing on rising ground, was one, a giant among giants. Its trunk was three feet in diameter and straight; its top symmetrical, and the whole sound to the core. It was shivered to fragments near the ground.

Since writing the above, a communication from Mr. Raiff of Sandyville, northeastern part of Tuscarawas Co., states, that the tornado passed about 1 mile south of that place at half past three o'clock P. M.; moving in a direction north of east, but gradually curving towards the east. It commenced southwesterly about 24 miles from Sandyville, and passed on to the east; in all a course of 17 miles. The direction corresponds with what has already been stated.

The roar of the tornado burst upon Brandon while the clock was striking 2 P. M. From this to Sandyville is 67 miles, which the storm swept over in an hour and a half; which gives a progressive velocity of 44 miles per hour. This corresponds very closely with the previous estimate, the difference being only one-third of a mile. The mode of action seems to have been the same; parts of buildings, it is stated, were carried to the north, some to the southeast, and others to the west of the foundations.