Speculum metal and steel have been tried for the cylinder faces, but only with moderate success.

If he cannot, let him concern himself with Cicero's definition, till he have strength to propose to himself a better, who would have a comedy to be invitatio vitae, speculum consuetudinis, imago veritatis; a thing throughout pleasant and ridiculous and accommodated to the correction of manners."

Comasque ad speculum disposuit.

Speculum tenui suspensum funiculo demittunt: et ad Cyaneas petras ad Lycicae fontes, &c. 2356.