1815.} Recovery of the Aachen Mass of Native Iron. 53 
There appears to be a singular increase of the variation in the 
month of April, more particularly so in May and June. Suspecting 
there might be some error, the source of which was in the instru. 
ment, but which I could not discover, I sent it to the maker, Mr. 
Dollond, who examined it, sharpened the point of suspension, and 
placed new agates in the needles, which alterations do not seem to. 
have affected the result of the observations. May it not therefore 
be justly inferred that the increase is real, and not apparent? One 
circumstance is indubitable, which is, that the vibration of the 
needle has been seldom, and of small extent, since the 20th of 
February last, on which day the needle vibrated between 28 and 29 
minutes. 
The immersion and emersion of » Cancri was instantaneous, and 
no diminution of the star’s light was perceptible. 
The dew which fell on the instrument rendered the observation 
on the 11th inst. doubtful to a few seconds. 
, Between noon of the Ist May 2 ,, 
Rain fallen ee noon of the Ist ed innit sigs 
Evaporation during the same period ..........2°70 
ArTICLE XI, 
Recovery of the Aachen Mass of Native Iron. In a letter from 
Dr. Benzenberg.* 
Kloster Briggen, near Crefeld, Dec. 15, 1814. 
You will already know that the great mass of native iron at 
Aachen, which had been lost, has been lately again found. I went 
last week to Aachen to see it, and can give you the following infor- 
mation respecting it. 
In the year 1762 Councellor Léber was with Maximilian Prince 
of Saxony at the baths of Aachen, as his physician. At the time 
they inhabited the house called Biichel, at the new bath, Léber 
observed in the pavement an uncommonly large iron-stone. He 
requested liberty to dig it up, obtained it, and took some specimens 
of it. He gave some of the smallest to the physician Dr. Kretsch- 
mann, in Dresden, whose collection of minerals came into the 
possession of the University of Wittenberg. ‘This information is to 
he found, in the Wittenberg Weekly Paper for 1773, page 36; 
from which it found its way into -he Memoirs of the Berlin Natural 
History Society, vol. vii. page $28. By a mistake of the writer in 
both accounts, Aken is substituted for Aachen; and Chladni, who 
mentions this mass of iron in his well-known treatise, considers the 
place as Aken in Magdeburg. Letters were written to Aken on the 
* Translated from Gilbert’s Annalen der Physik for Dec, 1814, vol, xlviii. p, 410, 
