May. 1911. 



KNOWLEDGE. 



181 



The planet is a very conspicuous object in the e\ening, 

 looking S.E.. rather low down; on May 1st he rises at 7.2 p.m.. 

 and throughout the month he has risen in the E.S.E. before 

 the Sun has set. 



The planet is describing a retrograde path near the star 

 X Virginus. 



On account of the belt markings on the disc, and his bright 

 satellites, this is the easiest and most interesting planet to 

 observe in small telescopes. The polar flattening is .also a 

 noticeable feature, since the equatorial diameter is 44" and the 

 polar diameter 2"-S smaller. 



The Great Red Spot has been difficult to observe during the 

 past few years, but the period deduced from observations ot 

 the spot give the planet's rotation as 9*^ 55"" 38*. 



The rapidly moving satellites present a diversity of con- 

 figurations in the same evening ; the following table gives 

 their principal phenomena observable before midnight. 



Uranus : 



" Oc. D." denotes the disappearance of the Satellite behind the dibc, and 

 ■ Oc. R." its reappearance ; '*Tr. I." the ingress of a transit across the disc, and 

 ** Tr. E." its egress ; "' Sh. I." the ingress of a transit of the shadow across the disc, 

 and "Sh. E." its egress; " Ec. D." denotes disappearance of Satellite Iiy Eclipse, 

 and " Ec R." its reappearance. 



Saturn : — 



Saturn is in conjunction with the Sun on May 1st, and 

 therefore unobservable during the early part of the month. 

 Towards the end of the month the planet is a morning star, 

 rising in the E.N.E. at 3.34 a.m., on May 21st. 



Uranus rises about midnight on the 20th May, and 

 about 11,18 p.m. on June 1st. The planet is Uiifavourably 

 placed for observation as he is low down in the sky : he is 

 describing a retrograde path in Capricornus about 2 S.E. of 

 cf Capricorni, 



Neptune : — 



Neptune is observable in the N.W, portion of the evening 

 sky, not far from Venus, and is in conjunction with that planet 

 on the 30th. The planet sets at 11.50 p.m. on the 15th. 



The planet is difficult to identify among the numerous small 

 stars appearing in the same field of view, as it requires a high 

 power (about 300) and good definition to distinguish his disc ; 

 he can, however, be detected by his relative motion if 

 observation be made on successive nights. 



Meteor Showers : — 



The principal shower during May is the Aqiiarids. This 

 may be looked for between May 1 to ft : the radiant being in 

 R.A. 22" 32" Dec. S. 2 . near the star v Aijuarii. 



Telescopic Objects: — 



Double St.\rs.— a Librae, Xl\"." 46'". S. 15 40', m.igs. 3, 

 6 : separation 230" ; very wide pair. 



ff Coronae, XVI.'' ll", N. 34' 8', mags. 6, 6i ; separation 

 5"-0; binarv. 



a Herculis, XVII." lo'". N. 14 30', mags. 2.1, 6: separation 

 4"- 8. Very pretty double, with good contrast of colours, the 

 brighter component being orange, the other blue. 



S Herculis, XVII.'' 11"". N. 24 57'. mags. 3. 8: separa 

 tion 14". 



Clusters. — M13 (cluster in Hercules) is situated about 

 one-third the distance from -q to s' Herctilis, and is just visible 

 to the naked eye. It is a globular cluster, and with a three or 

 four inch telescope the outlying parts of the cluster can be 

 resolved into a conglomeration of stars. 



QUERIES AXD .ANSWERS. 



Readers arc invited to send in Questions and to ansu-er the Queries which arc printed on here. 



QUESTIONS. 



35. MOVEMENT OF A TAUT WIRE.— \\'hen a taut 



wire, say a mile long, has a weight at one end and one pulls it 



a foot towards one at the other, does the distal end of the wire 



move at the same time .as the proximal in one's hand, or is its 



movement later ? t- r> 



Fr.\ncls R.\m. 



36. METEORS. — It is stated in most buoks on .\strononiy 

 that meteors are ignited by friction with our atmosphere at a 

 height of seventy miles sometimes. As the density at 

 this height does not amount to nearly the millionth of that at 

 sea level, can any of your readers explain how falling bodies 



could be ignited by such a rarefied atmnsphere, 

 that they move at the rate of forty-fi\e mile 

 maximuiTi speed for meteors ? 



even assummg 

 i a second, the 



' Puzzled." 



37. ROTATION OF STUFFED BIRDS .\TTACHED 

 TO WIRES.— The little birds, which are suspended by wires 

 in a case in the hall of the Natural History Museum, may be 

 observed very slowly to rotate, the tips of their wings describing 

 a quadrant of a circle, or more : and so they have done, I can 

 aver, for the last twenty years. What is the cause of the 

 movement? Fr.^ncis R.^m. 



