^{page 243 note *} Archaeologia, lvi, 290, et seq.

^{page 245 note *} The cementation process for the manufacture of brass, which was practised by the Romans and in England until recent times, was as follows : a mixture of granulated copper, charcoal, and calamine (an ore consisting of carbonate of zinc) was heated in a crucible ; the zinc in the calamine was reduced to the state of metal by the charcoal ; it then alloyed with the copper, forming brass.

^{page 245 note †} Vasco de Gama visited the east coast of Africa in 1497–8.