Progress of Astronomy during the Year 1879. 477 
his “Systema Saturnium” Huyghens describes a 23-foot tube, 
with which he observed Titan, and the eyepiece is described as 
follows: “Ab altera parte, que in nimirum oculo admovetur, 
bina sunt vitra minora, 1} pollicem diametro, equantia, juncta 
invicem, queeque hoe pacto eequipollent convexo colligenti radios 
parallelos ad intervallum unciarum 3 aut paulo etiam angustius 
Illud enim in Pioptricis nostris demonstratum in- 
venietur” . . .* The last words quoted show that the 
“Dioptrica” was already written in 1659 or earlier. As to Campani, 
who is also often supposed to have been the inventor of the 
negative eyepiece, Professor Oudemans requested Professor 
Schiaparelli to look over his work “ Raggualgio di due nuove 
Osservasioni ” (Roma 1665). The result was that Campani used 
a triple terrestrial eyepiece, which apparatus, however, was not 
invented by him, but as Professor Winnecke remarks (A. N. 
2292) by the monk Schyrl (Schyrlzeus de Rheita). 
In the same article Professor Winnecke also mentions a work 
by the same Schyrl, published in Louvain in 1643, and contain- 
ing observations of nine satellites of Jupiter, of six round Saturn, 
and of “nonnullae” round Mars. With respect to the five extra 
satellites of Jupiter, Scheibel informs us that Gassendi declared 
them to be nothing but Tycho’s stars, 24-28 Aquarii. Schyrl 
accepted this explanation also as regards Saturn and Mars. 
Herr Breusing, of Bremen, draws attention to Christophori 
Clavii Opera (1611) in which a vernier is distinctly described, 
except that it was not placed on the movable alidade, which 
latter idea originated with Vernier (A. N. 2289). 
“Obituary Notices of Astronomers” is the title of a little book 
by Mr. Dunkin, in which are collected some obituary notices of 
Fellows and Associates of the R.A.S. (by no means all astronomers), 
mostly written for the annual report in the Monthly Notices, but 
revised, and some of them partly rewritten. Some of the notices 
are rather meagre, for instance the one of d’Arrest, others are very 
full and interesting, especially those of the two Herschels and the 
Rev. R. Main. 
“Répertoire des constantes de l’Astronomie, par M. J. C. 
Houzeau,” occupies 271 pages in 4to of the Annales de l’Observa- 
toire Royal de Bruxelles, Nouvelle Serie, T. I. This is a most 
* (Opera varia, Lugd. Bat., 1724, p. 538-39. ] 
