160 A VOYAGE OF DISCOVERY 
come amalgamated with the lead, of which the 
artificial troughs generally used are made. * 
Tuesday, 30th. — The same thing was observed 
again this evening with regard to the mercury, for 
it became solid at the temperature (by a spirit 
thermometer) of 36° below zero. I do not men- 
tion this, however, as a matter of surprise, for it 
was the same mercury that was used last night, 
consequently it ought of course to freeze again at 
the same temperature. 
Wednesday, December 1st. — Between seven and 
eight o’clock this evening, four Paraselena, or 
mock moons, were observed, each at the distance 
of about 212° from the moon. One of them was 
situated close to the horizon, and another perpen- 
dicularly above it; the other two were one on 
each side of the moon, in a line parallel with the 
horizon. Their shape was somewhat like that of 
a comet, but they were incomparably larger, hay- 
ing their tails on that side farthest from the moon ; 
their colour was slightly prismatic, the side that 
was nearest the moon being of a light orange 
colour, which vanished Staal into a yeton 
towards their tail. 
Shortly after they were seen, a halo, or lumi- 
nous ring, having the moon for its centre, made its 
appearance; the radius of this ring was equal to 
the distance between the Paraselenze and the 
* That some impurity in the mercury is the cause of its 
freezing at such a low temperature is obvious, I think, from this 
circumstance, namely, that the mercury in the mercurial ther- 
mometer did not freeze even at 38°, and the temperature of 
the air was registered by it until it exceeded that cold. 
