3o8 



NA TURE 



[January 13, 1910 



" The honour of the invention, next to the Lord of 

 Merchiston,' and our Master Briggs, belongeth (if I have 

 not been wrongly informed) to Master Gunter who ex- 

 posed their numbers upon a straight line." He then 

 describes the advantages gained by sliding two Gunter 's 

 scales together, but points out the defects of this primitive 

 method, and so finally leads up to his circular slide rule. 



In the " Epistle Dedicatorie " to Forster's " Circles of 

 Proportion " an answer, said to have been given by 

 Oughtred to a question asking him the reason why he 

 had concealed his inventions so long, is quoted : — 



" That the true way of art is not by instruments but by 

 Demonstration ; and that it is a preposterous course of 

 vulgar Teachers, to begin with instruments and not with 

 sciences, and so instead of Artists to make their Scholers 

 only doers of tricks, and as it were Juglers ; to the despite 

 of Art, losse of precious time, and betraying of willing 

 and industrious wits into ignorance and idlenesse." 



Possibly another reason was the fear that his 

 parishioners and others might think that he might have 

 been better employed than inventing slide rules. Support- 

 ing this latter view is the fact that he published (1633) his 

 " Mathematicall Recreations " under the pseudonym of 

 Henry Van Etten. In this volume occurs the world-famous 

 arithmetical trick, "Think on a number, double it, &c." 

 It is highly probable that he invented it. 



I see no reason for doubting Oughtred's word that he 

 used sliding scales in 161S. The date of Wingate's re- 

 puted " discovery was thus anticipated by six years. A 

 perusal of Partridge's book published in 1671 shows that 

 the method of using compasses with Gunter's scales was 

 the one that was then generally employed in London. In 

 that year Partridge's slide rules were for sale at the shop 

 of Walter Hayes, at the Cross-Daggers in More-Fields, 

 next door to the Popes-Head-Tavern, London. 



Personally, I consider that Seth Partridge is the real 

 inventor of the modern lo-inch slide rule. 



.Alexander Russell. 



Faraday House, London, January 5. 



The Tercentenary of the Telescope. 



The article on the tercentenary of the telescope, pub- 

 lished in Nature of December 16, 1909, is extremely 

 welcome, not only because of its appositeness in point of 

 date, but because Dr. Dreyer sets in true light the nature 

 of Galileo's claims in connection with the discovery of 

 the telescope. I do not think that it can be denied that 

 Galileo himself makes the claim, for he puts into the title 

 of the " Sidereus Nuncius " the words " nuper a se 

 reperti." Nor can this be brushed aside as merely an 

 elliptical phrase, because it is pretty clear that he left 

 on the minds of the Doge and Senate of Venice the 

 impression that he had invented the instrument with which 

 he showed them the shipping. I deduce this from the 

 decree as gi\'en in a footnote by Mr. Fahie on p. 78 of 

 his admirable " Life of Galileo." 



Galileo seems to have known nothing about " the secrets 

 of perspective" as suggested in that decree; he describes 

 quite clearly that he did not reason from optics, but from 

 common sense ; and his optics were, in point of fact, 

 wrong when he asserted that one lens could not alone act 

 telescopically. It seems clear that he knew nothing about 

 the formation of an image by a lens. I confess that I 

 cannot see that he is entitled in this matter to so much 

 credit as Prof. Turner ascribes to him in a recent article 

 in the New Quarterly. 



In the matter of the satellites of Jupiter we tread on 

 much more certain ground, since it is now, I believe, 

 generalh' conceded that Marius, in his " Mundus Jovialis." 

 gives us a genuine account of his own observations. The 

 charge of plagiarism formulated by Galileo, and repeated 

 by nearly all his biographers, is now exploded. (Mr. Fahie 

 does not explicitly charge Marius with plagiarism, but 

 clearly he disbelieves the general truthfulness of the 

 " Mundus Jovialis." a position that, I feel sure, he would 

 ■abandon if he read what Messrs. Oudemans and Bosscha 

 have written.) Dr. Dreyer says that Marius found the 

 satellites one day later than Galileo, but when the actual 



1 Rather a grandiloquent method of referring to Jhone Neper, ' Fear' of 

 Merchiston. 



- " Le Calcul Simplifii-." By M. d'Ocagne. (1905.) 



NO. 2098, VOL. 82] 



records are compared it becomes clear that Galileo was, 

 on the contrary, at least two days behind Marius. From 

 Galileo's account in his Italian MS. notes, reproduced by 

 Prof. Favaro in his national edition, we see that it was 

 on January 11 that he first suspected the three " stars " 

 to be satellites. (The " Sidereus Nuncius " suggests 

 January 10 for the first suspicions.) Thus Galileo saw 

 them as stars on January 7, and as satellites on January 

 10 or II. Now Marius saw them as stars some month 

 or so earlier, and on January 8 he discovered their true 

 nature. Thus it is hardly fair to compare the dis- 

 covery as satellites made by Marius on January 8 with 

 the mere detection as " stars " made by Galileo on 

 January 7. For the fourth satellite Galileo is entitled to 

 the priority. 



I dislike as much as anyone all quarrels about priority, 

 and only direct attention to these facts because of 

 Galileo's hostile attitude. His genius and his intuitive 

 perception of the ways of nature will gain for him for 

 ever the admiration of all men, but his arrogance and 

 jealousy in these two matters make it incumbent on us to 

 be much more critical than in ordinary cases, and particu- 

 larly so because such fair-minded biographers as Mr. 

 Fahie speak of " his right to the first discovery " of the 

 satellites, and everyone uses the phrase " Galilean 

 telescope." J. A. Hardcastle. 



The Dial House, Crowthorne. 



Cross-fertilisation of Sweet-peas. 



Under *he above heading a writer in Nature of 

 January 6 (p. 280) refers to " the statement that the sweet- 

 pea is invariably self-fertilised," a statement which he 

 thinks is " often based on an opinion of Charles 

 Darwin's." In refutation of this opinion your corre- 

 spondent describes the visits of the hive-bee and of 

 Megachile to the flower in question. These same species 

 were seen by Mr. Darwin to visit sweet-pea flowers 

 (" Cross and Self-fertilisation," 1876, p. 156). He goes 

 on to ask how it is that the varieties are not habitually 

 mongrelised. and sums up his discussion in the following 

 words : — " Whatever the cause may be, we may conclude 

 that in England the varieties never or very rarely inter- 

 cross. But it does not follow from this that they would 

 not be crossed by the aid of other and larger insects in 

 their native country, which in botanical works is said to 

 be the south of Europe and the East Indies. Accordingly 

 I wrote to Prof. Delpino, in Florence, and he informs me 

 ' that it is the fixed opinion of gardeners there that the 

 varieties do intercross, and that they cannot be preserved 

 pure unless they are sown separately.' " 



January 10. Francis Darwin. 



May it be allowable to point out that " tt," who has 

 contributed an interesting note (Nature, January 6, p. 280) 

 on the "Cross-fertilisation of Sweet-peas." is not the 

 same who (vol. Ixxii., p. 631) is responsible for the 

 " Rhymes on the Value of v "? 



The Original " t." 



A Hardy Goldfish. 



Can one of your readers please explain the following 

 incident? 



I keep some goldfish in a glass bowl. On December 

 31 last one of them was seen lying motionless upon its 

 side on the surface of the water. After about an hour, as 

 it was thought to be dead, it was removed to a shelf, 

 remaining there for three hours. My sister then picked 

 it up to throw it away, but was surprised to find it open- 

 ing its mouth and breathing. She placed it in fresh water, 

 when at first it lay on its side, occasionally moving its 

 head and fins. The water presently appeared to be slightly 

 tinged with the golden colour of the fish, which suddenly 

 turned over on to its back, the ventral surface being 

 upwards, and remained thus for some time. On being 

 transferred to another vessel, the fish, assuming the normal 

 position, swam about leisurely for a little while, and 

 gradually recovered its usual energy, being now equal to 

 any of its old companions. 



Was this a rase of paralysis, cramp, or other temporary 

 ailment, and what enabled the fish to remain so long alive 

 out of its natural element? G. C. Constable. 



50 Clonmel Road, South Tottenham, January 4. 



