2S6 



NATURE 



[January 17, 189 = 



so, whether his star is not a new satellite. He further pro- 

 ceeds:— " I am bold the rather to mention this as an inquiry 

 whether any such number of Sitellitesor moons hathbeenc scene 

 by your honor or Mr. Roolce [? Hooke] or any mathematitians or 

 other gentlemen that have good tubes and often have the 

 curiosity to view the planet, for possibly it may be new to me 

 which hath beene more usually ItnoAne by others, though the 

 notion of such a ihinije is not new to my selfe, for I remember 

 I mett with the like narration many years since in a little 

 booke in'ituled PhilosophiaNaturalisperJoh. Phociliden, though 

 then I thought that was but a mi-take of some fixed Starrs." 

 Now that Prof. Barnard ha- discovered a genuine filth satellite 

 of Jupiter after the lapse of nearly three centuries since Galileo's 

 telescope detected the Medicean stars, a greater interest is given 

 to those imaginary satellites which from time to time have 

 claimed a place in the solar system. In .-i paper in the Johns 

 Hopkins University Cir.iilar for last May (referred to in 

 Nature, vol. I. No. 12S3, p. ii3\ Mr. Frank H. Clutz has 

 given a probable identification of Winthrop's supposed satellite 

 with B A.C. 644S In a postscript to his article it is pointed out 

 ihit the work to which Winthrop refers is presumably the 

 " Philosophia Naturalis, seu Physica Vetus-Nova '' of Johann 

 Kokkens (born at Holwarden in Frieiland in 161S ; died at 

 Franeker, February 19, 1651). At President Oilman's sugges- 

 ti m, I have followed up this clue, and have succeeded in 

 examining the work in question. I find that it contain- more 

 than a casual reference to additional satellites of Jupiter ; in 

 fact, a whole chapter is devoted to a discussion of certain ob- 

 servations, which seems to be sufHclently interesting to deserve 

 a 'lief notice. 



r.iocylides' treatise was published at Franeker in 165 1, shortly 

 after the death of the author. On the title-|>age it is described 

 a; wr iten "Ab Eximio Viro/JoH Phocyliue Holwarda/ 

 L .\. M. Med. Doct. & Philosophiae,/dum viveret, Proless. 

 Ordinario." There is also a portrait. The third of the three 

 parts into which the book is divided is entitled " Physica Cte- 

 testis, " and it is doubtless this portion of the Philosophia 

 which Winihrophad in mind when writing his letter to Sir Robert 

 Moray. It is not Phocylides himself who claims to have dis- 

 covered new moons of Jupiter ; nor does he believe in their 

 cx:stence. On the contrary, he treats the supposed ob-ervaiions 

 with the severest disapprobation ; and while in general he is 

 enthusiastic over the revelations which the telescope had 

 already made and was daily making, this particular di>covery, 

 which he regards :is spurious, rouses him to the mosi strenuous 

 exertions in order to efi'ect its refutation The discoverer, by 

 -Tme .-Vntonius Maria Schyrleus dc Kheita, stated that he had 

 en, not one, but five new satellites of Jupiter, all farther 

 I'-moved from the planet than the four Galilean tn ions, ami 

 revolving in a contrary direction. Phocylido' account ol the 

 matter may be briefly summarised as follows: First he refers 

 to five stars near a certain kntjwn s'ar ol the four h magnitude. 

 They are "intra duodecimum <S decimum quinium Pi-cium 

 gradum " (p. 205) "versus sinisiram secundum Signorum suc- 

 cessionem." (p. 205 and p. 2S4.) 



These stars, he continues, have given rise to no little con- 

 troversy among learned and experienced astronomers (astro- 

 philos,' whether they are fixed stars or erratic, and, more 

 particularly, whether Ihry are companions (commilitune>) of 

 jupiier. The iliscusiion ol this point is then posiponed. 

 Ch.ipter xvi. treats of the number of the planets and iheir 

 division in kind. Doth satellites and planets proper are in- 

 clu'led in the term "planct.-e. " .Mier rejecting the sun from 

 his ancient place among the seven planets, and adiling 10 their 

 number the two lalcronts atioul S.iturn and the four ab ju' 

 Jupiter, discovered in ihc "current century by ihe aid of nevi- 

 and admirable instruments, such as Tubi Ojitic , specula, and 

 oiheriol the same son," hr adds the Earth to the twelve hitherm 

 ciljtaincd. It is thus ccriam, he says, that there are at least 

 ihirlr'-n planets, sine-; it is not yet known whether Mars, Venu-, 

 anri Mercury have any ia/erottts rev -Ivirig an lut them. " lin 

 as to the five other circuinjovialcs which P. An'on. M.ir. d 

 l<hcii:i lioasts that he has observed and called Urban Oc a- 

 viaii.t, learned men are justly in doubt whether they should \» 

 referred to the fixed or 10 the wa'.dering stars." Nothing; 

 fiirihcr is aHile<l at this place, but he prr>ceed- to divide ih> 

 tliiriccn planets into primary anil secon^lary. The former (>ix 

 in nunifier) arc named in order from Mercury to Saturn, wrd 

 the Faith in the Sun's former place. 1 he l.itter ate .Saturn'- 

 two, anil Jupiter's four satelliies. The seventh is the Moon 

 Anyone who doubts this, he ailils, will be convinced by what ii 



NO. 131b. vol.. 51 j 



soon (o be said, as well as by the onsiderations contained in 

 the chapter " De Lunni; corpore & motu." After several 

 interesting chapters, including one on Saturn and his laterones, 

 and another on Jupiter and the Medicean stars, we come to 

 chapter xxi., entitled " De Pseudojovialibas : & priorum 

 consectaria." Phocylides' attitude is at once disclosed. He 

 refers to the pseudo-discoverer as "quidam .\ntonius Miria de 

 Rheiia, (homo in Pap.itu arrogans, invidus, judicio proeceps & 

 fatuu', aliorum gloriam pro propria injusie & cu n pudoris 

 oblivione captans & vindicans)." 



The discovery was alleged to have been made at Cologne near 

 the end of the year 1642, and was announced in a letter to 

 Puteanus. Hut it so h.ipjiened that Hevelius had noticed and 

 described these very stars several months previously. His 

 observations were mule in August 1642 and the succeeding 

 mmihs, and Phocylides regards the claims of Rheita to have 

 been the first to discover them as " freiidum mendacium," as, 

 by his own admission, he did not ob-erve them before the end 

 of the year. The identity of Rheita'- peu'lo joviales with 

 these fixed stars is shown by a omparison of the actual 

 positions of Jupiier on the dates when Ihe observations were 

 made. Our author poin s out that on Decem*ier 29, the day 

 ol Rheita's discovery, Jupiter occupied the same position as 

 on the previous 4th of St-p ember, when Hevelius observed him 

 and noticed the five stars. This position is defined by Pho- 

 cylides in the words, " decimo tertio gradu Piscium, cum quin- 

 decem minutis. " Again, Heveliu- saw Jupiter on .-Vugust 28 

 " in dtcimo quarto gradu Piscium, cum quindecem minutis," 

 where Rheiia observed htm on January 4 ol the following year 

 (16 (3). The new circum-'oviales ate then, says Phocylides, 

 none other than the stars recently discovered in .\quarius. 

 They do not move round Jupiier, as they would do if ihey 

 were second \ry planets, and are therefore fixed stars, " mane- 

 buntque [fixx-| usque ad sxculi consunimationem." They were 

 observed by Hevelius to remain stationary, while Jupiter left 

 them behind him. Phocylides challenges any doutiter to look 

 for these stars himself, when all five will be lound in their 

 original position and at the same distances one from another. 

 He concludes with the words (p. 289); " llallucinatur iiaque 

 cr.i-se & inani ui'n - i;lor o .1 Rtieiia se ipsum utilUi." 



Tne following will ihow furiher li^hl on Rheita's 

 tendency 10 fo m hasty conclusions. According to Phocylides 

 he declared that he had ob-erved three of the Medicean stars 

 t) be in a straight line, but the loirth "tanlam obiinuisse lati- 

 tudinem, qua;, -i ex centro Jovis liccentricum ad ilium excur- 

 rentem mctiamur, ad qum lecein gradus excrescat." This, says 

 our author, is contradictory to the tibservations ot all " mathe- 

 maticians," who unintmiusly agree that the .Medicean stars 

 never recede from Jupiter in latitude more than three minutes, 

 whether to the no'th or to the south. He then s'aies that this 

 fourth star, s > far from being a true Galilean satellite, wis not 

 even a pseudo-jovial, but another fixed star. Gas-endi observed 

 the satellites on the same night, and saw all four in a straight 

 line, the second lightly to the north ; but they were ilifferently 

 dis osedwith regard to Jupiier. In all i)robal)ibty, Phocylides 

 concludes, the fir.st (innermost) satellite was obscured by the 

 planet, if, as is likely, the observations were not made at pre- 

 cisely the s.imc hour j for Jovial Mercury (is he is called) runs 

 his course roun<l Jupiier in a few hours more than a wliole d.iy. 

 Pnocylt'les supposes tna', as Rheita was well aware ihii there 

 *er^ four satellites, he mistook this fixed star for the fourth 

 -atcllite. 



Tne existence of Rheita's new satellites was opposed by 

 Gassendi in his " Juilicium dc novem stcllis ciica Jovem visis 

 (-ee Drlam'irc, "llis. dc ^A^t. Mod.," ii. p. 351), and by 

 Hevelius in his " Selenograiihia," ih. p. 437). l.obko«ilziu» 



■ lefcmled Rh-ita against Ga.sen li (" Ph .cylides," p. 295). 

 Delainbre devotes several partes to Rheita, or Sohyrle, cik' 

 i;iv s some av:count ol his work " Oculus Kioch et lilirf, sive 

 l< idius siilere iniysticus." Antwerp, 1645. In this book, 

 a,.cjrding to Delamore, he admits .hat dc has not 



■ uccci^ded in oiiserving his satellites agnin, but asserts 

 a lew that he noticed changes in their mu ual distances. 

 He explains their di-appeatancc by connec ing ihetn with 

 v.irialile stars, which he supposes to have l.irgc orbits and long 

 rev.d.ilions. He believed, moreover, thai the spots of the suns 

 *cre pi met-, an I that the -un i sell rotated lUi once in a year. 



Phocylides also mcniioi.s circuin-inar tales ami circuin- 

 -.iluinales, which, no less than the ciicunijovi.iles, must be 

 held to lie lixcd stars. 



Ii will thus ue »een that VVinlhrop was ri^hl in remembering 



