August 2, 1897.] 



KNOWLEDGE. 



189 



practice. I constructed sundry rough models worked by 

 hand, purchased lantern slides, maps, telescope, etc.; but 

 everything was destroyed by fire, and I am not at liberty 

 to make a fresh start on those lines. 



I think that anyone interested in the subject, and having 

 time at his disposal, should call a public meeting to discuss 

 the idea, the preliminaries, and the practicability ; and I 

 think also that the establishment of such an institution 

 would nobly commemorate this auspicious year. 



G. E. Lavalette, B.Sc. 



[I am not quite clear which object Mr. Lavalette has in 

 view — whether he wishes to spread a knowledge of what 

 we may call the popular side of astronomy, or to extend an 

 acquaintance with the details of its progress — necessarily 

 often involving highly technical explanations — or whether 

 he desires to found a school for practical observation. In 

 the last case, he must bear in mind that in any serious 

 sense it is impossible to democratize science, and especially 

 astronomy. Practical observation can only be learnt by 

 practical work in an observatory, and observatories will 

 always be few in number, as they are necessarily costly 

 and great centres of population are the worst possible 

 sites for them. Nor can they ever be available for use by 

 the many, since practically there can be but one observer 

 at each telescope at a time. The British Astronomical 

 Association has in contemplation the erection of a students' 

 observatory in the Kegent's Park for the benefit of its 

 members. Should this scheme be carried out, it will 

 probably meet the needs of all those whose circumstances 

 permit them to make serious use of it. 



If Mr. Lavalette's idea is rather to promote a knowledge 

 of the details of astronomical progress, this could un- 

 doubtedly best be met by a multiplication of lectureships 

 like that so admirably fiUed by Mr. Ledger at Gresham 

 College. These consist of three series of four lectures 

 each in the year, at the by no means exorbitant cost of 

 £'100 per annum. It would, however, be inappropriate to 

 ask the Government to endow a number of such lecture- 

 ships, but it would be every way advantageous if local 

 bodies were to found them. Lectureships of this order 

 might well be attached to the great free libraries. The 

 analogy of the Gresham Lectures would seem to show 

 that they should be free, and should be designed to give 

 real and serious instruction, and that the expense to the 

 public body supplying them need not be great. I should 

 wish Mr. Lavalette every success if he should endeavour 

 to get this idea adopted. If, however, his idea is first of 

 all to amuse, and mere popular presentments of astronomy 

 are all that he desires, I think we may confidently look to 

 the ordinary caterers for public entertainment to provide 

 as much of this class as the public are ready to take. 



The project of a wmeum does not exactly commend 

 itself to me as applicable to astronomy. I fail to see what 

 working models could be supplied except orreries — ^justly 

 called " foolish toys " by Sir John Herschel, and more 

 misleading than helpful — or models of telescopes which 

 would need explanation from some qualified attendant. 

 Both orreries and telescope models would be far more 

 useful as adjuncts to the lectures. 



It is unfortunate that the only point upon which Mr. 

 Lavalette is thoroughly definite is that of Sunday 

 opening — a point which would certainly call forth opposi- 

 tion. But we fancy that an enterprise now successfully 

 at work in the Urania Steruwarte, Berlin, might meet his 

 wishes. Here are four refractors and one reflector on view 

 any tine night at the small fee of sixpence, and from time 

 to time lectvu^es are given in the accompanying theatre 

 illustrated by mechanical and photographic shdes, so as to 

 give as perfect a representation as possible of the most 



striking phenomena which the heavens have to show 

 us. — E. Walter Maunder.] 



THE "TEN COMMANDMENTS." 

 To the Editors of Knowledge. 



SiBs,— A phrase which Mr. George Morley, in his 

 interesting articles on "The Language of Shakespeare's 

 Greenwood," says is " directly conveyed from Shake- 

 speare," is at least older. He quotes from the Second Part 

 of King Henry VI. (Act I., Scene 3) the lines : — 



" Could I come near your beauty with mv nails, 

 I'd set my ten commandments in your face." 



But the expression is to be found in an earlier anonymous 

 play printed in London in 1596, entitled "A Pleasant 

 Conceited Historie, called ' The Taming of a Shrew.' As 

 it was acted by the Eight Honorable the Earle of Pem- 

 brook his servants." There is a copy of this curious 

 quarto in the British Museum. In this comedy, which 

 differs considerably from Shakespeare's later comedy, 

 Kate is made to say to her boisterous wooer Ferando : — 



" Hands off, I say, and get you from this place ; 

 Or I will set my ten commandments in your face." 



West Hampstead, SILVA^'us P. Thompson. 



July 9th, 1897. 



SUNDIALS. 

 Mr. Charles Atkinson, of Tockwith, York, writes asking 

 for information as to how to correctly set a sundial. 



[There are several kinds of sundial, and Mr. Atkinson 

 leaves it in doubt as to which kind he wishes to adjust. 

 The horizontal sundial motmted on the top of a short 

 pillar is so much the most common that I will assume it 

 to be the kind in question. 



A dial has two parts — the style or rod which casts the 

 shadow, and the engraved dial plate which receives it. 

 The line on the plate bearing the figure XII., marks the 

 meridian. It is from this line that the style rises, and 

 the plane passing through this line and the style must be 

 at right angles to the dial plate. This is the first point to 

 be verified, and an ordinary square will at once show if 

 the style is in adjustment. 



The next point is that the dial plate must be truly 

 horizontal. This can be tested by a spirit-level. Thirdly, 

 the style must be inclined to the plate at an angle equal to 

 the latitude of the place ; a dial, therefore, is suitable for 

 use only for that special latitude for which it was con- 

 structed. 



Lastly, the style must be brought into the meridian, and 

 when this is done the style will point to the North Pole of 

 the heavens. 



To bring it into the meridian it is necessary to know the 

 time of local apparent noon. This we can ascertain if we 

 have a watch or clock showing the exact Greenwich time, 

 and if we know the longitude of our station and the equa- 

 tion of time. The longitude of York is 4m. 18s. west of 

 Greenwich — that is to say, it is noon at York at 4m. 18s. 

 after twelve at Greenwich. On August Ist, as any 

 almanack will show, the sun is slow by the clock 6m. 6s. 

 Therefore, at 10m. 23s. after noon by a watch keeping 

 precise Greenwich time, the sun will be on the meridian of 

 York on August 1st. At this moment, therefore, the dial 

 plate must be turned until the shadow of the style lies 

 precisely along the central line and points to XII. 



It may, perhaps, be well to add that, in the case of a dial 

 engraved for one latitude, it is not sufficient in order to 

 adapt it for another to alter the angle of the style. It is 

 suitable only for the latitude for which it was engraved. 



