390 PHILOSOPHICAL TRANSACTIONS. [aNNO I677, 



•' On four Sorts of factitious Shining Substances. N° 135, p. 867. 



Two of these four substances have been already noticed in two of the late 

 Transactions, viz. N° 131, and N° 134; one of them being the factitious paste 

 of Dr. Baldwin, shining in the dark like a glowing coal, after it has been a 

 while exposed to the day or candle-light; the other, the Bononian stone cal- 

 cined, which imbibes light from the sun-beams, and sq renders it again in the 

 dark, whereas the former needs no sun-shining. To these we shall now add 

 two other sorts. The one is by the Germans called phosphorus smaragdinus, 

 said to be of this nature, that it collects its light not so much from the sun- 

 beams, or the illuminated air, as from the fire itself; seeing that, if some of 

 it be laid on a silver or copper-plate, under which are put some live coals, or 

 a lighted taper, it will presently shine; and if the same matter be shaped into 

 letters, they may be read.* The other is called phosphorus fulgurans, which is 

 made both in a liquid and dry form ; and not only shines in the dark, and com- 

 municates a sudden light to such bodies as it is rubbed on, but being included 

 in a glass-vessel well closed, it now and then fulgurates, and sometimes rises 

 as it were into waves of light. It is further said, that a little portion of it 

 having been kept two whole years, has not yet lost its power of shining : so 

 that it is believed, if a considerable piece of it were prepared, it would serve 

 for a perpetual, or at least a very long lasting light. 



Observations of the late Comet, made at Paris by Signor Cassini, N° 135, p. 868. 



Translated from the Latin, 



M. Romer first obser\^ed the new comet, April 28, N. S. 1677 ; and, 

 having presently informed me of it, at 4^^ Q^ 31® after midnight, we took its 

 altitude \1° 22' 10''. I judged it to be in a vertical, declining about 33° from the 

 east .towards the north. — On the 29th it was seen by M. Picard for a moment 

 through the clouds, at 3^ 9"^ 31^ after midnight, at an altitude of 4° 39'. 



May 2d in the morning, the right ascension of the mid-heaven by the 

 fixed stars being 267°, the altitude of the comet was 4° 5': the distance of 

 the vertical about 42° 8' from the north towards the east. — May 4, at 3^ 30"", 

 the comet's altitude was 5° 33'; the distance of the azimuthal from the north 

 towards the east about 42° 32'. — May 5, at 3^ 32"", the comet's altitude was 

 5° 10'; the azimuthal distance from the north to the east about 44° 10^ 



* The substances here enumerated make but a very small part indeed of the number of mineral 

 bodies which, under certain circumstances, become luminous in the dark. See Mr. Thomas 

 Wedgewood's experiments on the production of light from different bodies by Iieat and attrition, ia 

 the 82d volume of the Philosophical Transactions. 



