ee 
Mineralogy and Geology. 449 
’ M:€=136°. Now 42 (4-@) in Type III, makes an angle 
with $-2 (Scacchi’s n°)* of 134° 23. Again, M:é==157°, and this 
is very nearly the angle of 42 (4-@) on $ or 4 (r* or r® of Scacchi). 
But the inclination of €:& over a is 127°; and this equals nearly the 
angle between 4-5(n°) and 4(r°), one above and the other below the 
plane of the lateral axes, this angle being according to our calculation 
126° 52’. Considering the dissimilarity of the three types in Humite 
and the unevenness of the surfaces measured, the coincidences are as 
tlose as could be expected. 
Again, the prism a bas the angle 85°; and calculation gives for the 
corresponding angle of @-3 in humite (a plane not given by Scacchi 
but between his o and 02), 85° 34’. There is also another plane (4) in the 
figure of chondrodite which is probably the brachydiagonal. prism 4-, 
judging from the inclination of this plane on the edge between & and é, 
Which according to the writer’s observation was 168°. . 
Note on Tabular Spar or Wollastonite; by J. D. Dana.—ln the 
usual mode of viewing the crystals of this species, the relation to Py- 
foxene which exists is not shown. But making the clinodiagonal the 
vertical axis, there is then a vertical prism of 87° 28’ (e, e’, in Brooke 
and Miller’s figure), varying but 23 minutes from that of pyroxene. 
The inclination of the axes is 69° 48 The vertical axis in tabular 
Spar is about one-fifth shorter than in ordinary Pyroxene, and this is 
main point of distinction in the form of the crystals. 
2. Notice of a crystal of Fischerite; by Nicnoras Koxscuarov, 
(communicated for this Journal.)-—-The Fischerite occurs in small trans- 
lucent crystalline plates and crystals in the fissures of a ferruginous 
and for the other 99° 56’ (mean of 8 trials). The first measurements 
should have the preference ; and taking the prism as the prism of the 
fundamental series, we have, for the vertical (a) and lateral axes (4, c) 
the ratio a:b:ce—2:168196:1 i é 
also the prism or P—118? 32’ and 61° 28’, and the prism &P3—99° 524’ 
and 80° 74’; ¢P: Px =120° 44, aP¥: aPe —189° 56}. 
Te esttidonsl 
* Tn sis ’s figures, his planes 7, are made of the general form 
wi in thts a, of See IPS: aiid Yas ma of the form mP3, In givitig: the 
raphic symbols above we omit the P. 
+t In the analyses of humite, p. 279, Fe, should be Fl. 
Srrizs, Vol. XV, No. 45.—May, 1853. 58 
