# Lumen Australe Romae Observatum Die 27 Jan. An. 1740. a Didaco de Revillas, Abbate Hieronym. P. Math. Prof. & R. S. S.

**Author(s):** Didaco De Revillas  
**Year:** 1739  
**Journal:** Philosophical Transactions (1683-1775)  
**Volume:** 41  
**Pages:** 4 pages  
**Identifier:** jstor-104360  
**JSTOR URL:** <https://www.jstor.org/stable/104360>  

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Light on the common Classics, to which I have confined this Examination, and which must be my Excuse for the Citations. I am, with great Respect,

The Royal Society's

and your most obedient

humble Servant,

E. Latham.

XV. *Lumen Australe Romæ observatum die 27 Jan. An. 1740.* a Didaco de Revillas, Abbate Hieronym. P. Math. Prof. & R. S. S.

COELO undique nubilo, notoque vehementer flante, hora post Meridiem 6a. rubescens lumen inter gradus 45 & 55 amplitudinis ortivæ australis apparebat. Maxima ejus supra horizontem latitudo gradus circiter 9 æquabat. Parte tamen Coeli horizonti proxima ad unum circiter gradum obtenebrata spatium fere parallelogrammum gradus 10 latum, 8 altum lumini concedebatur; quod in suprema parte magis, minus in ima splendescet. Inter densiores nubes altera summe nigricans *AB* TAB. VI. Fig. 3. horizonti propemodum parallela, supra lumen, meridiem versus protendebatur.

Post horæ semissem vividius sensim micabat splendor; sensimque iterum minuebatur: quod pluries usque ad horam 9 observatum. Interim tenuis horizonti
zonti itidem parallela nubecula C.D lumen a meridionali plaga intersecans, comparebat. Circa horam 9 nubes aliæ ab orientali versus meridionalem plagam paullatim procedentes splendorem jam languescentem obtegebant: & circa horam 9 ½ penitus extinguebant. Post horam 12 largus imber decidebat.

Barometrum toto hoc tempore ad altitudinem pollicum Parisin. 27. 9 ¼ consistebat. Thermometrum mercuriale (quod in aqua ebulliente notat gr. 0.; in nive vero salis communis duabus quintis partibus permixta, gr. 180) designabat tunc temporis gr. 141.

Monemus interea lumen hocce nedum splendididius, verum & eminentius visum eodem tempore, & ad eandem plagam ab nonnullis Viterbio ad Urbem accedentibus, ac ab aliis in Via Valeria (hoc est, ad orientem Romæ) quinto supra vicesimum ab eadem urbe millario iter facientibus.

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Corrigenda in Philos. Transactions, No 459.
Page 646. Line 12. for 10° 02' 00'' read 10'.
647. Line 7. for Oct. 28. read 27 Oct.
648. Line 9. for 15h 53' 4'' read 15h 55' 4''.

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