[502] Hardouin, according to his usual custom, employs all his learning and ingenuity to give a plausible explanation of this passage. Alexandre, as it must be confessed, with but too much reason, remarks, “Frustra desudavit Harduinus ut sanum aliquem sensum ex illis Plinii deliramentis excuteret.” He correctly refers the interval of time, which was said to occur between these signals, not to any astronomical cause, but to the necessary delay which took place in the transmission of them. He concludes, “Sed ad cursum solis hoc referre, dementiæ est. Nam ut tanta horarum differentia intersit, si moram omnem in speculandis ac transmittendis signis sustuleris, necesse erit observatores illos ultimos 135 gradibus, id est, sesquidimidio hemisphærio, a primis distare furribus. Recte igitur incredibilem Plinii credulitatem ludibrio vertit Baylius in Dictionario suo.” Lemaire, i. 389. [503] The distance, as here stated, is about 150 miles, which he is said to have performed in nine hours, but that the same distance, in returning, required fifteen hours. We have here, as on the former occasion, a note of Hardouin’s to elucidate the statement of the author. On this Alexandre observes, “Optime; sed in tam parva locorum distantia, Elidis et Sicyonis horologia vix quinque unius horæ sexagesimis differre poterant; quare eunti ac redeunti ne discrimen quidem quadrantis horæ intererat. Ineptos igitur auctores sequitur hoc quoque loco Plinius.” Lemaire, i. 390, 391. [504] “Vincunt spatia nocturnæ navigationis.” This expression would appear to imply, that the author conceived some physical difficulty in sailing during the night, and so it seems to be understood by Alexandre; vide not. _in loco_. [505] “Vasa horoscopica.” “Vasa horoscopica appellat horologia in plano descripta, horizonti ad libellam respondentia. Vasa dicuntur, quod area in qua lineæ ducebantur, labri interdum instar et conchæ erat, cujus in margine describebantur horæ. Horoscopa, ab ὥρα et σκοπέω, hoc est, ab inspiciendis horis.” Hardouin, in Lemaire, i. 391. [506] These distances are respectively about 38 and 62 miles. [507] We are not to expect any great accuracy in these estimates, and we accordingly find, that our author, when referring to the subject in his 6th book, ch. 39, makes the shadow at Ancona 1/35 greater than the gnomon, while, in Venetia, which is more northerly, he says, as in the present chapter, that the shadow and the gnomon are equal in length. See the remarks of M. Alexandre in Lemaire, _ut supra_. [508] This would be about 625 miles. Strabo, ii. 114, and Lucan, ii. 587, give the same distance, which is probably nearly correct. Syene is, however, a little to the north of the tropic. [509] This remark is not correct, as no part of this river is between the tropics. For an account of Onesicritus see Lemaire, i. 203, 204.