34 



KNOWLEDGE & SCIENTIFIC NEWS. 



[I^ebruarY, 1907. 



interest pertains to observations this season on account 

 of the brightness of the maximum. Such a bright 

 maximum is not hkely to occur uiulcr ciiually favourable 

 conditions more often than once in twenty years. It is 

 to be hoped, therefore, that those who have made careful 

 observations will publish the results, and thus contri- 

 bute towards a solution of that great problem, the cause 

 of variation of these mysterious bodies. 



.\ provisional curve is given herewith, which shows 

 the general nature of light change during the past six 

 months, and, for comparison, an approximate curve for 

 the preceding season is superposed, the months being 

 the same for both. These curves are based upon 85 

 observations made by the writer in Spain. Those for 

 the present season are appended in tabular form. The 

 magnitude scale is that of tlie Harvard College Observa- 

 tory, and Harvard magnitudes have been adopted for 

 the comparison stars used. When possible, stars similar 

 in colour were used for comparison purposes in preference 

 to white or bluish stars. The change of colour is not 

 the least interesting feature of variable stars. Most of 

 them are red or orange, and some appear to become 

 redder as maximum is approached, but Mira, inten.sely 

 ruddy in its fainter stages, loses much of its colour when 

 the brightness increases. On September 15, the colour 

 w-as noted as a strong red, but about the time of maxi- 

 mum it had changed to a rather pale yellowish orange. 



Observations of Mira, I906-7. 



New Prism Binocular. 



Messrs. .\. E. St.aley and Co., of 19, Thavics Inn, Holborn 

 Circus, E.C., have sent us for inspection a new prism 

 binocular, of the type now so popular, made by the firm of 

 E. Krauss and Co., Paris, for whom Messrs. Staley are the 

 British representatives. The binoculars magnify eight 

 times, and have an adjustable milled bar for focussing, 

 which moves both oculars, whilst one ocular has, in addi- 

 tion, a graduated adjustment to enable a difference in the 

 sight of the eyes to be separately rectified. The glasses are 

 also adjustable for width between the ej-es— an equally im- 

 portant matter. A minor improvement is a stud enabling 

 the binocular to stand upright on a table without damage. 

 The definition of these glasses is excellent, and they are 

 very' light, compact, and daintv, so that thev could be used 

 either out of doors, for which thev are, of course, primarily 

 intended, or in a theatre. The price, moreover, is onl'v 



X.0 lOS. 



The Bride-Stones — Cleveland Hills. 



By E. J. SuMNEK, B.Sc. 



TiiEkE arc sexeral groups of stones in various parts of 

 the Cle\ eland Hills which arc known as Hride-Stones, 

 of which the most im|)()sing are tho.se which look down 

 on the head of the \allev nrimed from thom — St;iindale 

 — about 8 miles north-east of l'ick<'ring. 



The photogr;i|)li shows in the foreground one of the 

 c|uaiiilest of thes<' stones, known as the " .Salt-cellar," 

 and to the loft of it, more distant, is visible a round 

 boss of the '' Chcesewring " type. The matcri;d is a 



kind of gritstone, belonging to the oolitic series of 

 rocks, and consists of a number of layers of greatly 

 \arying hardness. It is generally supposed that the 

 sea is responsible for these curiously formed rocks, for 

 they resemble those upon which the sea is engaged 

 on the Vorkshire coast at the present day, though, of 

 course, the weathering action of wind, rain, and frost 

 w ill have largely altered them since the time when the 

 sea left them in their rough-hewn state. 



The "'Salt-cellar" is some 20 feet high, about 10 

 jards round the waist or lowest part, and 20 or 30 

 3ards round nearer the top. 



Some particulars have been published of the abortive experi- 

 ments in Transatlantic wireless telegraphy which were cut 

 sliort by the fall of the tower at Machrihanish. Messages 

 had been received and sent between Machrihanish on the 

 Mull of Cantyre, and Brant Rock, near Boston, U.S.A., but 

 it was found subsequently that not sufiicient allowance had 

 been made for the atmospheric absorption of the Hertzian 

 waves on all occasions, and in possibly unfavourable condi- 

 tions. At 1,500 miles 10 per cent, of the radiation got 

 through ; but when 3,000 miles was the distance it was 

 found that not i per cent, of the radiation could always be 

 depended upon. Indeed, during daj'light the absorption was 

 sometimes so great that not more than one-tenth of i per 

 cent, of the energy got through. As an illustration of the 

 complexities of atmospheric interference it is stated that, 

 with the same sending power, on some nights messages 

 were received 4S0 times stronger than was necessary for 

 audibility, and the messages could be read with the receiver 

 six inches away from the ear. On other nights with the 

 same sending power the messages were so faint that they 

 could not be read. A satisfactory factor of safety in trans- 

 mission had been achieved when the antennse blew down. 



