91. Cubic fragments of common galena, (sulphuret of lead). Kanem, Soudan.
92. Pure tin, cast in moulds, in the form of thick wire. Brought from Soudan.
I conclude this long letter with mentioning a specimen of Roman cement, taken from the ruins of Ghirza, which, in parts where the admixture of small stony fragments is not observable, has very much the appearance of, and might easily be mistaken for, a granular-crystalline variety of tertiary limestone. It has unquestionably undergone a transformation: a circumstance which may, in some measure, serve to justify the remark of Lepère—“C’est le temps seul et non l’art qui manque à la pétrification absolue de nos mortiers et cimens; nos neveux diront de nos constructions ce que nous disons de celles des anciens.”
I have the honour to be, my dear Sir,
Yours very faithfully,
Charles Konig.
To Major Denham, &c.
FOOTNOTES:
[126]Three very interesting bivalve shells, distinct, it appears, from the other species of the genera to which they respectively belong, have been discovered in the above-mentioned river by Major Denham. The first, a species of Ætheria, I distinguish as
Ætheria Denhami: testa irregulariter rotundato-oblonga, ad cardinem gibbosa, utriusque valvæ callo cardinali basim versus oblique truncato.