O. N. Rood—Improvement in the Sprengel Pump. 57 
6. Fergusonite _— Mitchell County, North Carolina, and 
dentical with Rutherfordite 
I ee signed along with the daitibgskeite of this locality a 
few very small crystals “of fergusonite poeey resembling those 
sHsihelly described by Haidinger as coming from Greenland, 
and nearly identical with those found in the sands from the 
gold washings of Rutherford, N. C., named by me as ruther- 
fordite, and ‘which I now consider as elortity to the species 
fergusonite. 
7. Green Pagodite in Georgia. 
A very handsome green variety of this mineral is found on 
Beaver-dam creek, nine miles west of Washington. It first 
sahietous: with a pines fracture. Very tough. It is more 
often freckled and blotched with a.copper-red rutile ; the latter 
impurity sometimes imparting after polishing, a resemblance to 
blood-stone. Hardness =3. Gr.=2°86. Before the blow-pipe 
in thin fragments, turns white and suffers slight fusion. Colors 
borax, apple-green. Uniformity of composition bi rio ow- 
ing to presence of muscovite and rutile. The trials gav 
Si 48° to 52°, aie sete Fe 2°10, slab ate K 4-43, 13-5, 
nd Ti undetermin 
It probably forms a stratum of jokuidbeabis dimensions in a 
mica-slate formati 
New Haven, May 8, 1880. 
ART, VIL. —On an improvement in the Sprengel Pump ; by 
Professor O. N. Roop, of Columbia College. 
In this notice I propose to indicate very briefly the nature 
of an improvement that I have lately made in the form of the 
Sprengel pump, which enables the experimenter easily to obtain 
a vacuum as high*as 90,000,000 2° 190,000,000" reserving the details 
of manipulation, e etc., for more extended notice hereafter. 
1.) The improvement consists, first, in an arrangement by 
means of which the mercury, instead of being at once introduced 
into the ws ce passes beforehand through an exhausted bulb 
gains ud in great measure from air and moisture. 
