While looking through a window, Kayser, the Polish astronomer, saw a fireball appear at Rigel and move to Sirius, where it disappeared. This observation of his proved to be one of the most accurate and _significant_ ever made of the fall of a meteorite. For it enabled the German mathematician, Galle, to show that the Pultusk meteorite, which produced the fireball Kayser saw, came into the Solar System from interstellar space! It is very essential to carefully notice and mark the exact spot from which your observation was made so that you can return to it if scientists wish to set up surveying instruments there. The map and side view of the Norton County, Kansas, meteorite trajectory show the practical results that the Institute obtained by use of the intersecting-lines-of-sight method. The fireball accompanying the Norton meteorite fall appeared at A. The first “explosion” took place at E₁, the second at E₂, and the fireball disappeared at L. If markers were dropped straight down to earth from each point along the trajectory or flight-path of a meteorite through the atmosphere, the line joining the points where the markers fell would be the _earth-trace_ of this trajectory. The directions of sight to these various points are indicated for people living in the towns along and near the earth-trace of the Norton meteorite fall. The solid-line arrows represent the direction of the point of disappearance; the dotted-line arrows, the point of appearance; the dash-dot arrows, E₁; and the dashed arrows, E₂. The probable area of fall is shown as an oval-shaped area, the longer axis of which is identical with the direction of motion of the meteorite. [Illustration: Path of the Norton meteorite.] The many fragments of all sizes recovered from the Norton fall were all found within the bounds of this oval-shaped area, although unavoidable errors of observation placed the center of the oval about 4 miles too far to the north. In addition to the questions about direction and elevation, there are a few more that investigators of meteorite falls would like to have observers answer. At what time (determined as accurately as possible) did the fall occur? Knowledge of this time is necessary if the path in which the meteorite was moving about the sun is to be calculated by scientists. Did you hear any sounds, either while you were watching the fireball or after it disappeared? If you heard such sounds as the whining or hissing of meteorite fragments flying through the air or the heavy thumps of their impacts on the earth, then you were very close to where the meteorite came down! How many minutes and seconds (again determined as accurately as you can) passed between the time when you saw the fireball vanish and the instant when you first heard sounds from it? Such sound data permit rough determination of the distance from the observer to the point where the meteorite fell.