1810.] 
eal observations and reasoms, in re- 
‘searches which relate to the body, or re- 
“strict the application of them to certain 
diseases. It would be usefal to discuss 
‘these two opinions, to shew and esia- 
‘blish more clearly how far psychology 
and natural philosophy may be combined, 
‘and todemonstrate,by historical evidence, | 
what each of these sciences has hitherto 
contributed to the advancement of the 
other. 2. The idea of an universal and 
characteristic language proposed by Leib- 
nitz, having never been sufiiciently ex- 
plained by himselt, and appearing to 
have not been understood by any person, 
the’ question is, to give an accurate and 
Juminous designation of that language, 
to point out the way that is capable of 
leading to this desirable object, and at 
the same time to exatnine how far the 
methods hitherto tried in certam sciences, 
for instance, iv mathematics and chemis- 
try, might be correctly applied to philo- 
sopliy and the other branches of jiuman 
knowledge. For the best answer to each 
of these questions, the academy offers a 
‘gold medal of the value of 4fty Danish 
ducats. Answets to all, except the last, 
the term of which is extended to 1811, 
must be sent before the conclasion of 
‘1810, either in Latin, French, English, 
German, Swedish, or Danish, to M. 
‘Buycr, professor of astronomy at Co- 
penhagen. 
ROYAL SOCIETY OF LONDON. - 
Dr. Wottraston has lately given an 
account and description of. a reflec- 
tive Goniometer, to he applied to the 
measuriig of angles of crystals. By this 
‘Instrument, in most cases, the incliwation 
of surfaces may be measured as exactly 
as is wanted for common purposes, and 
when the surfaces are sufficiently smooth 
to reflect a distinct image of distant ob- 
jects, the position of faces oniy z45ch > of 
an iach in breadth may be determined 
with as much precision as thosé of any 
larger crystals. For this purpose, the 
ray of livht reflected from the surface 
is employed as a radius, instead of the 
s face itself; and fora radins of oth of 
‘an inch, we tay substitute either the 
‘dstance of the eye from’ the crystal, 
which would naturally be about twelve or 
fifteen inches; or by a second mode, 
substitute the distance of ubjects seen at 
a hundred or more yards from us. The 
‘Instrument consists of a circle graduated 
on its edge, and mounted on a horizon 
tal axle, ‘sapported by an upright pillar. 
This axle being perforated, admits the 
Montaty Maz, No. 203. 
Royal Society of London. | 
-tion, 
-without coinputation. 
“ment a perfectly clean and uniform frac. 
149 
passage of a smaller axle through it, to 
which any crystal of moderate size may 
be attached by a piece of wax, with its 
edge, or intersection of the surfaces, hi- 
rizontal and parallel to the axis of mvs 
The position of the crystal is first 
adjusted, so that by turning the smaller 
axle, each of the two surfaces, whose 
inclination 1s to be measured, will reflect 
the same light to the eye. ‘Vhe circle is 
then set to zero or 180°, by an index 
attached to the pillar that supports it. 
~The small axle is then turned, till the 
farther surface reflects the light ofa cans 
dle, &c. to the eye; and lastly, the circle 
is turned by its larwer axle, till the second 
suriace reflects the same light. ‘This 
second surface is thus ascertained to be 
in the same position as the former surface 
had been. ‘The angle through which the 
-eircle has moved, is the supplement to 
the inclination of the surfaces; but as 
the graduations on its margin are name 
-bered accordingly in an inverted order, 
the angle is correctly shewn by the index 
By this instra- 
ture is not neces:ary, fer’since all those 
sinall portions of a shaitered surface, that 
are parallel to one another, glisteir at 
once with the same hght, the angle of an 
‘irregular fracture may be determined 
nearly as well, as when the reflecting 
fragments are actually in the same plane, 
The inventor of this goniometer thinks 
the accuracy of it to be such, ‘that a cir- 
cle of moderate dimensions, with a ver- 
nier adapted to it, will probably afford 
corrections to many former observations. 
‘He adds, that he has already remarked 
one imstance of a mistake that prevails 
respecting the common carbonate cf 
lime, which he particalarly mentions, 
because this substance is very likely to 
be employed as a .jt-of the correctness 
of such a gomometer, by any one who 
1s not convinced of 1t8 accuracy from a 
distinct canception of the principles of 
its construction.’ The inclination of the 
suifaces of a primitive crystal of carbo- 
nate of lime, is stated to be 104° 23/ 407, 
a result deduced ‘from the supposed posi- 
tion of its axis, at dnangle of 45° with 
each of its surfaces, Dr. Wollaston 
contends, that the anvle is not 45° ex- 
actly, but 45° 20/,.for he finds the ineli- 
nation of the surfaces to each: other is 
nearly, if not accurately, 103°, as it was 
formerly determined to be by Huygens; 
‘and since the measure of the superficial 
angle, given by sit Isaac Newton, corres. 
ponds with this determination of Huy- 
U gens, 
