My readers here will undoubtedly call to remembrance the source of taxation devised by the emperor Vespasian, who, as his historians tell us, _urinæ vectigal commentus est_[253]. It is not certainly known in what manner this impost was regulated. Did the emperor declare that article, which was not _subterraneum rarius_, to be a regale as a _res derelicta_, so that the scourers were obliged to pay him what he thought a reasonable sum proportioned to the benefit which they derived from it? Or was it imposed only as a poll-tax? For every tax upon anything indispensably necessary to all, is, to speak in the language of finance, the same as what is called a poll-tax, or a tax paid by every one who has a head. The latter conjecture is the most probable, especially as this tax continued two centuries, till the time of Anastasius, and as we read also of _vectigal pro urina jumentorum et canum_, which was exacted from every person who kept cattle. Vespasian therefore was not fortunate in the choice of a name for his tribute, which on that account must have been undoubtedly more detested. A poll-tax at present is called by those who do not speak favourably of it, the Turkish-tax, because the Turks impose it on all unbelievers. When it was introduced by Louis XIV. in 1695, he called it _la capitation_. Of plants with a saponaceous juice, the ancients, at any rate, used one instead of soap; but it is difficult or rather impossible to define it. I shall not therefore content myself merely with transcribing the passages where it is mentioned, but I shall arrange whatever I can find respecting it in such a manner, as, according to my opinion, the names of plants ought to be explained in dictionaries. Στρουθίον, Struthium, Latinis Herba lanaria, et Plinio etiam Radicula. 1. Est planta spinosa, _Theophrastus_, _Plinius_. 2. Grata aspectu, sed sine odore, _Theophrastus_, _Plinius_. 3. Folio oleæ, _Plinius_; vel papaveris Heraclei, _Theophrastus_. 4. Caule ferulaceo, tenui, lanuginoso, eduli, _Plinius_. 5. Radice magna, acri, medicinali, _Plinius_, _Dioscorides_; spumescente, _Lucian_. 6. Floret æstate, _Theophrastus_. _Plinius_; sed semen nullum, _Plinius_. 7. Nascitur saxosis et asperis locis, _Plinius_. 8. Sponte, præcipue in Asia Syriaque; trans Euphratem laudatissima; sativa ubique, _Plinius_. 9. Radix conditur ad lanas lavandas, _Theophrastus_, _Plinius_, _Dioscorides_, _Columella_, et alii. 10. Herba ovibus lac auget, _Plinius_.