igitur de conjugiis et divortiis eorum erga lucem, atque eorundem conjugiorum et divortiorum gradibus. Flamma spiritus vini, aut ignis fatui, longe ferro ignito calore lenior est, verum lumine fortior. Cicendulæ et rores aquæ salsa, et multa ex illis quæ enumeravimus, lucem jaciunt, calida ad tactum non sunt. Etiam metalla ignita tenuia non sunt, at calore tamen ardente prædita. At contra aër est inter tenuissima corpora, sed luce vacat. Rursus idem aër, atque etiam venti, motu rapidi sunt, lucem tamen non præbent. At contra, metalla ignita motum suum hebetem non exuunt, lucem nihilominus vibrant.

In cognationibus autem lucis, quæ non ad generationem ejus, sed ad processum tantum spectant, nihil tam conjunctum est quam sonus. Itaque de eorum sympathiis et dissidiis accurate videndum. In his conveniunt. Lux et sonus in ambitum circumfunduntur. Lux et sonus per longissima spatia feruntur, sed lux pernicius; ut in tormentis videmus, ubi lux citius cernitur quam auditur sonus, cum tamen flamma pone sequatur. Lux et sonus subtilissimas distinctiones patiuntur; ut in verbis articulatis soni, in omnibus visibilium imaginibus lux. Lux et sonus nihil fere producunt aut generant, præterquam in sensibus et spiritibus animalium. Lux et sonus facile generantur.et brevi evanescunt. Nam non est quod quis putet sonum illum qui ad tempus aliquod a campana aut chorda percussa durat, a prima percussione fieri. Nam si campana vel chorda tangatur, et sistatur, sonus statim perit. Unde manifestum est, durationem soni per successionem creari. Lux a majore luce, sicut sonus a majore sono, obruitur; et cætera.

Differunt autem, quod lux (ut diximus) sono velocior sit. Lux majora spatia vincat quam sonus. Lux utrum in corpore aëris deferatur, quemadmodum sonus, incertum sit. Lux in linea recta tantum, sonus in linea obliqua et undiquaque, feratur: etenim cum quid in umbra umbraculi cernitur, non est quod quis putet quod lux ipsa penetret umbraculum, sed aërem tantum circumfusum illuminat; qui etiam aërem pone umbraculum vicinitate nonnihil illustrat: at sonus ab uno latere parietis redditus, ex altera parte parietis auditur, non multum debilitatus. Etiam sonus intra septa corporum solidorum auditur, licet exilior factus; ut fit in sonis infra lapides hæmatites, aut in corporibus percussis infra aquam; at lux in

So Gruter's copy: the words durationem soni are omitted in Rawley's. — J. S. VOL. II.

Y

corpore solido et non' diaphano, undique obstructo, omnino non cernitur. Ultimo, quod omnis sonus generetur in motu, et elisione corporum manifesta; lux non item.

At hostilitates lucis, nisi quis privationes pro hostilitatibus habere velit, non occurrunt; verum quod maxime credibile est, torpor corporum in partibus suis maxime est luci inimicus. Nam fere nihil lucet, quod non aut propria natura insigniter mobile est; aut excitatum vel calore vel motu vel spiritu vitali. Alia.

Intelligo autem semper, quod non tantum aliæ instantiæ investigandæ sint (istas enim paucas exempli loco solummodo adduximus) sed etiam ut novi topici articuli, prout rerum natura fert, adjiciantur.

1 So Gruter's copy: the words solido et non are omitted in Rawley's. — J. S. Gruter's copy has Lux magis in profundum penetrat quam sonus; ut in fundo Omnis sonus generatur, &c. — J. S.

aquarum.

SYLVA SYLVARUM.

PREFACE

TO

THE SYLVA

SYLVARUM.

BY ROBERT LESLIE ELLIS.

IN 1627, the year after that in which Bacon died, his chaplain Dr. Rawley published the Sylva Sylvarum. The preface is Rawley's own, and was written in Bacon's lifetime; it gives some account of Bacon's views touching the kind of natural history required as the foundation of the instauration of the sciences, but contains little or nothing which is not found elsewhere. Although Rawley says that in the present work the materials for the building are collected, yet it cannot be doubted but that Bacon was fully conscious that, even taken in conjunction with the treatises De Ventis and De Vitâ et Morte, &c., the Sylva Sylvarum falls far short of his own idea of a just and perfect Natural History. We should do him injustice if we were to suppose that he was satisfied with the collection of facts here published, of which much the greater part are taken from a few popular writers. We ought rather to regard it as a proof that Bacon's thoughts were busied, up to the close of life, with his plan for the reform of philosophy, and as the work of a man who, knowing that he could not accomplish his own designs, was yet resolved, in spite of worldly troubles and of increasing infirmities, to labour on in the good cause which he had so long had in hand. That it was Bacon's last work gives it a peculiar interest, though the habits of thought which in the seventeenth century made it a popular book have long since passed away. Curiosity about isolated or slightly connected facts seems gradually to decline, as scien