V. That the Author’s Advice of taking the Figures in Course, be strictly follow’d in the Practice; which will be a great means to render the Whole easy and pleasant.
This is the Sum of what we thought most proper to advertise you; and have only this farther to request, That if any Mistakes may have escap’d the Press undiscover’d, as we well hope there are few or none, you will favourably correct and pardon them.
MONITA ad TYRONES.
Concinnitatem ac symmetriam opticæ delineationes ædificiorum habere nequeunt, nisi utramque mutuentur ab Architectura. Proinde necesse est, ut in istius graphide ac intelligentia te aliquandiu exerceas, donec uniuscujusque elevationis vestigium formare didiceris, ex eoque eruere sectionem totius longitudinis, ut in Opere toto videre est, præsertim figuris sexagesimaoctava & septuagesima. Siquidem ex vestigio & ex sectione derivatur in opticas imagines congrua rerum singularum profunditas.
Subjiciam his consilium summi momenti; videlicet, egregiè intelligas oportet figuram secundam, priusquam progrediaris ad tertiam, idemque de cæteris dictum velim; nam singulas eo disposuimus ordine, ut quæ præcedit, necessaria sit ad percipiendas eas quæ sequuntur. Si aliqua sint in explicatione, quæ initio non intelligas, ipsum schema sæpius diligenter inspicies; ac vicissim si aliqua desint in schematibus, ex declarationibus ea supplebis. Lapsus verò quos deprehenderis, facilè pro tua benignitate, mihi, ut spero, condonabis.
ADVICE to BEGINNERS.
The Perspective of Structures here treated of, can have no Grace or Proportion, without the Help of Architecture. ’Tis therefore absolutely necessary, that you employ yourself for some time in Drawing, and the Study of that Art; till you can readily describe the Plan of any Upright, and from thence project the Section or Profile, as is shewn through the whole Course of this Work; and more particularly, in the Sixty-eighth and Seventieth Figures: Forasmuch as the proper Depth of each Part of the Perspective, is determin’d by the Plan and Profile thereof.