Goniome- 
ter. 
Burrow’s 
goniometer. 
PLATE 
CCLXXVIL. 
Fig. 11. 
Fig. 12. 
Brewster’s 
goniometri- 
cal telescope, 
Fig. 13. 
GON rr 
sured, be detached, it is obvious, that, if an acute one; 
by applying it to the angle BAD, the vertical and equal 
angle EAC will be given on the quadrant ; if obtuse, 
by applying it to the angle*E and B, we obtain its su 
chosent EAC. But if the crystal be imbedded in the 
matrix, so that with the common’ goniometers having 
the moveable vertex, it is difficult to procure a mecha- 
nical measurement of the protruding angle, we take 
any distance from the vertex of the crystal measured 
upon the scale of tenths, &c.; and placing one point 
of the instrument, (ex. gr.) on « { ig. 12.) and the 
other on 2, soas to make the triangle a yz isosceles, we 
get upon the quadrant the angle which the base 2 z sub- 
tends at the radius one inch; and we have the side 
ty measured. As, therefore, when the object is given, 
j 1 
andl rad. 
tion cy: AB:: angle found: angle sought. And as the 
the angle it subtends, , we have the propor- 
‘whole radius is one inch divided into tenths, this pro- 
.portion is easily made in the head. 
The short bar is added for the better carrying of the 
‘quadrant; and renders the instrument useful in geolo- 
gical observations, to ascertain the inclination of stra- 
ta, This is done by hanging a small plummet to a hook 
at A, and having made the angle which it forms at BC 
a right angle, and moving the outer bars, till their u 
per line coincides with the stratum, the angle of incli- 
nation will be given on the quadrant.” 
We shall now conclude this article with the descrip- 
tion of a goniometrical telescope, and a goniometrical 
microscope, invented by Dr Brewster, and described in 
his Treatise on New Philosophical Instruments. 
This instrument is represented in Fig. 13, where TT 
is the eye-tube of the telescope, which carries the gra- 
duated circle AB, divided into 360 degrees. By means 
of the milled head which surrounds the e e-glass at E, 
this circle has a motion of rotation about the axis of the 
eye-tube, The vernier.V has likewise a motion round 
‘the axis of the instrument, and may be set to the zero 
-of the scale, when.the level L, fixed to the plane surface 
of the graduated circle, is adjusted to a horizontal line. 
On the same surface, parallel to the axis of the level, 
there are fixed two-screws, (one of them is seen at 5) 
.on which the arm DF may slide to or from the eye-glass 
E. This arm is bent into a right angle at D, and car- 
vies a frame, in which the small reflecting plane O, 
made of black glass, is fitted so as to have a rotatory 
motion about the axis ab. 
When an angular object appears in the field of the te- 
lescope, the arm DF is pushed backwards or forwards, 
‘till the mirror O is near the centre of the eye-glass, and 
it is then turned round its axis ab, by means of the le- 
ver f, till the observer, by looking through the éye- 
glass, and into the mirror at the same time, perceives a 
distinct reflected image of the field of view, and the an- 
gular object which it contains. The graduated circle 
AB. is then moved round its centre, till the reflected 
image of one of the lines which contains the angle is 
continuous with the line itself, and the degree pointed 
out by the index is noted down. The circle is again 
made to revolve till the image of the other line is con- 
tinuous with the line itself, and the place of the index 
is again marked. The arch of the circle intercepted be- 
tween these positions, is the measure of the angle requi- 
red. To save the trouble of reading off a second line, 
the vernier may be placed at the zero of the seale, when 
the first coincidence has been observed. 
In order to explain the theory of this instrument, let 
ABC, Fig. 14. be a plane angle seen in the field of the 
telescope, and MN the section of a reflecting mirror, 
838) 
GOR 
which moves along with the graduated circle. - When Got 
the side BC is in the same straight line with its image 
CE, BC is perpendicular to reoasagr reps d " 
evid bw 
the quate a 
angular motion of the mirror, in passing sin 
Son (MD tacones is at aieeeed iartionerin en 
formed at the centre O by AO and CO, but by the an- 
gle FOG, which is equal to ABC. This will be evi- 
dent from considering, that the lines AB, CB are pa- 
rallel to FO, GO, and that the same angle would have 
Q' 1s 
measure of the angle formed by the lines AB, 
) 
The goniometrical mi 
15, and is nothing more than 
ceding contrivance to a microscope. 
Journal, Jan. 1809, vol. xxii. p. 1. and 
tise on New Phil: Instruments, p. 97—106, 110. Mae 
GONORRHGEA. See Mepicine and Surcery. | 
GOREE, is an island in the Atlantie; on the west 
coast of Africa. It is about 80 leagues from Senegal, 
about 1 league from the Terra Firma of my erd, and 
about 3 leagues from that Cape itself. The island is 
about 800 yards long and 240 broad, and is surround- 
ed on all sides by inaccessible rocks, excepting ‘in one 
small place to the east-north-east, contained between two 
points, one of which is high and the other flat, and co- 
vered with a bank of sand. This place forms a natural 
and secure harbour, A late director of the island, M. 
de St Jean, erected . — fort, oe me 
discovered spri of good water, an nted av; 
of vegetables aad fruit trees. The ae cool and tem~ 
perate during the whole of the year; and the inhabi-~ 
tants are refreshed by alternate breezes from the land 
and sea. . ; 
This island was ceded to the Dutch in 1617, by Bi+ 
ran, king of Cape Verd. It was immediately strengths 
ened by Nassau Fort on the north-west, and afterwards 
by Orange Fort, a little nearer the shore. In 1663, * 
Admiral Holmes took it from the Dutch. In 1666, it 
was retaken by Ruyter; but:in 1677 it was taken, after 
some resistance, by the French under the Count D’Es- 
trées. The English took the island from the Freuchin 
1692, and restored it in 1693. Since that time, it con= 
tinued in the possession of the French with a few ins 
terruptions, and was guaranteed to them by. the treaty 
of 1783. It was taken by the British in the late war. — 
West Long. 179 24 45’, and North Lat. 14° 40/ 10% 
Those who wish for very particular information respect- 
ing Goree, may consult Prelong’s Memoire sur Goree, 
in the Annales de Chimie for 17938. : eis te 
GORITZ, Gonz, or Gorrrta, is a town of Germany, 
situated in a district of the same name. The town is 
handsome, and is picturesquely situated on the river Li- 
sonzo. A great numberof the houses are good, and be- : 
long to calle families. It has seven convents, nine cha- | 
pels, and a college. ‘The opera-house, though not very 
neat without, is elegant and commodious within. The — 
fort commands an extensive view over the surrounding 
country. On the north side of the town are eminences 
of moderate height, affording all the characteristicsiofthe — 
icripaisinliisdeataia liniocas ecdaetien ee)? a ae 
