Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/253

Nothing having been said in my papers on the oxide of tin, and the sulphate of barytes and quartz, on the mode of cleaving them, they are now placed in the following table at the head of the ten substances forming the particular objects of this communication, chiefly to allow the opportunity of saying a few words on the subject of splitting them.

				Measurements.
Substances	Primitive Crystal.		Reference to Plate 12	According to Haüy	According to Bournon	By the Reflecting Goniometer
Oxide of Tine	An obtuse octohedron of which the common base of the pyramids is square	$\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}$	Fig.1 P on P	67° 42′		67° 50′
	Haüy		P on the opposed plane over the apex			112° 50′
Sulphate of Barytes	A right prism, with rhombic bases.	$\left.{\begin{matrix}\ \ \end{matrix}}\right\}$	Fig. 2. M on M	101° 32′ 13		101° 42′
	Haüy		M on the adjacent plane, over the edge A	78° 27′ 47		78° 18′
Quartz	A slightly obtuse rhomboïd	$\left.{\begin{matrix}\ \ \end{matrix}}\right\}$	Fig. 5. P on P	94° 24′		94° 15′
	Haüy		P on P'	85° 36′		85° 45′
Zircone	An obtuse octohedron; the common base of the pyramid is square.	$\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}$	Fig. 1. P on P	82° 50′		84° 20′
	Haüy		P on the opposed plane over the apex			95° 40′
Staurotide	A right rhomboidal prism		Fig. 2. M on M	129° 30′		129° 20′
	Haüy		M on the adjacent plane over the edge A			50° 40′
Anatase	An acute octohedron; the common base of the pyramid is square.	$\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}$	Fig. 4. P on P	137° 10′		136° 47′
Specular Iron	A slightly acute rhomboid. Haüy	$\left.{\begin{matrix}\ \ \end{matrix}}\right\}$	Fig. 3. P on P	87° 9′		86° 10′
				92° 51′		93° 50′
Diopside	An oblique rhomboidal prism. Haüy	$\left.{\begin{matrix}\ \ \end{matrix}}\right\}$	Fig. 6. M on M	87° 42′		87° 5′
			M on the adjacent plane, over the edge A			92° 55′