Page:Scientific Memoirs, Vol. 2 (1841).djvu/101

Rh In Munich, besides Prof. Steinheil, MM. Hierl, Lamont, Lippolt, Meggenhofen, Mielach, Pauli, Pohrt, Recht, Schleicher, Schröder, Siber, and Zuccarini.

Other observations of some of these six terms have also come to our hands, but too late for insertion in the plates; this is the more to be regretted, as, for the most part, they accord with the others in a very interesting manner. The results of the observations made at Upsala, in the September term, 1836, which are of this kind, are printed in the sequel. The Milan observations of November, 1835, which were also received after the curves for the six other stations had been drawn on stone, were inserted below them; but for this circumstance, their place would have been between the Munich and Palermo observations. The Göttingen observations have required no process of reduction, being drawn in accordance with the divisions of the scale as indicated in the margin, the height of each square being taken as two divisions of the scale in all the terms, with the single exception of that of January, 1836. The changes during that term are the greatest which have been hitherto observed, and rendered it necessary, in order not to increase the height of the page too much, to allow three divisions of the scale for each square. Increasing numbers always denote an advance of the needle from right to left,—in other words, diminishing westerly variations. The observations at Breslau, Freiberg, the Hague, and Leipzig, where the divisions of the scale are nearly of the same magnitude as in Göttingen, have been drawn according to the same proportion. The distance between the curves is an arbitrary quantity in each case, determined solely by its fulfilling the one object of keeping them at a convenient distance apart.

For those stations where the value of the divisions of the scale differs considerably from that at Göttingen, the original numerical results were multiplied in each case by a common factor, expressing, as nearly as possible, in convenient numbers, the proportion to the Göttingen scale. Thus, the various curves in each term are represented very nearly according to a common scale. In the January term alone the scale of representation is somewhat more unequal, the cause of which does not merit any mention in this place, as it suffices to know the scale for each curve. In the three first terms the height of each square corresponds to the following values of arc, viz.: