290 On a luminous Appearance 
sible, the wear to which they are exposed; and on 27th March 
1821 they were taken up and examined by the Committee of 
Manufactures. On minute inspection, they appeared to be about 
half worn out, and there was no very perceptible difference in 
the condition of each. 
With regard to the relative expense of procuring and preparing 
the two articles for manufacture, the Society possess no very cer- 
tain data; as the use of the Typha was at first set on foot chiefly 
in order to employ those parish poor who would otherwise have 
been idle. Two guineas were paid by Mr. S. for liberty to cut 
as much of the Typha as he pleased from about ten acres of 
swampy land near Hammersmith. The matting has been sold 
at from 9d. to 15d. per yard, and between 1000 and 1500 yards 
have been disposed of during the last three years. 
The Typha abounds in all marsh ditches and uncultivated 
swampy ground in every part of the kingdom ; whereas the Scér- 
pus is found in quantity sufficient for manufacture only in cer- 
tain districts: hence the former must be much more accessible 
and cheaper than even the Scirpus of home growth; and the So- 
ciety indulge the hope, that, by giving this notice a place in their 
antiual volume, the knowledge and the use of so abundant and 
cheap a material may be extended throughout the kingdom, and 
may form a means of domestic employment to the younger mem- 
bers of poor families. 
LXVI. On a luminous Appearance seen on the dark Part of 
the Moon in May 1821. Communicated in a Letter to the 
Rev. Dr. Pearson, from the Rev. M. Warp *. 
Dear Sir,— HAVE this moment laid aside my telescope from 
an examination of the moon. The atmosphere was more fa- 
vourable for the purpose than I have observed it to be for many 
weeks; and as it so happened, that at about the same age of 
the last moon, I had carefully examined the part in obscurity to 
look for a voleano, and had not in any part observed a remarka- 
ble appearance, I was greatly surprised to find a paragraph in 
the public papers, giving a detailed account of a volcano near 
Aristarchus, seen on the very night I had satisfied myself that 
there was not even an appearance which could be mistaken for 
a volcano. I resumed the attempt this evening; and having 
passed the enlightened part of the moon from the field, and care- 
fully avoided looking at it, to Have my eye in the best state to 
discover any more conspicuously illuminated spot in the unen- 
lightened part, I soon saw Aristarchus very clearly, having very 
* From the Memoirs of the Astronomical Society of London. 
much 
