Jan. 30, i88S.] 



SCIENTIFIC NEWS. 



57 



TOTAL ECLIPSE OF THE MOON. 



'X'HERE will be a total eclipse of the moon on the 

 evening of Saturday, the 2Sth inst., visible from our 

 hemisphere. Lunar eclipses can only take place when 

 the moon is near the spot where her orbit seems to in- 

 tersect the sun's apparent path in the heaven. On this 

 occasion the middle of the eclipse will occur only a few 

 minutes before the moon is at this point, known as her 



In 1877 at mid-eclipse the moon was of a beautiful 

 copper-red colour, but at the last eclipse visible in 

 England the moon was nearly invisible. On that occa- 

 sion, according to some observers, a bright blue rim to 

 the shadow was noticed a little before and a little after 

 totality. During totality the small amount of light that 

 was visible was of a greenish tint, but the form of the 

 moon could hardly be made out. Other observers noticed 

 curious changes in the depths of the shadows during the 



Di.\cRAM Showing the Formation of the Umbra and Penumbra. 



node, so the eclipse will be practically a central one, and 

 consequently one of long duration. 



The phenomena of a lunar eclipse can be best ex- 

 plained by means of the accompanying diagram, where S 

 represents the sun and E the earth. The rays AB CD, 

 coming from the sun, and touching the earth at the points 

 B and D, cast a shadow of the earth in the form of 

 a cone, BED, which has its apex at a point, F, some- 

 where in space. Other beams coming from the same 

 points on the sun's surface, AD CB, also cast a shadow 



total phase. A total eclipse of the moon also gives a 

 good opportunity for observing the occultations of small 

 stars, as, owing to the absence of moonlight, the observa- 

 tions can be made with great accuracy. 



THE NEW CHROMOMICTOR.— II. 



MR. AITKEN mentions a v.;ry beautiful experiment 

 which can be made with his new apparatus. 

 This may be interesting to our readers. If, after having 



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—ir 



-K 



,~S 



Sectional View of Chronomictor. 



Fig. 4. End View. 



contained within the lines B G and D H, thus forming a 

 partially illuminated fringe round the central cone, which 

 is known as the penumbra, the central shadow being 

 termed the umbra. 



The moon will enter the penumbra at 8.19 p.m., at 10.31 

 it will meet the earth's shadow, will be central at 1 1.20, will 

 quit the shadow at 12.9, and be clear of the penumbra at 

 2.1 1 a.m. on Sunday morning. The phenomena attending 

 a total eclipse of the moon are by no means so striking 

 as those accompanying a total eclipse of the sun, but yet 

 there are several points worthy of careful observation. 



adjusted the colours to produce white, dull black screens 

 be slipped on the two interior sides of the box, and an 

 opaque body be introduced into the lower compartment, 

 there is at once formed a striking display of prismatic- 

 like colours. The paper on the bottom of the box is no 

 longer white, but covered with most varied and 

 brilliant hues, caused by the penumbra of the opaque 

 body being lighted with different colours on the different 

 sides. Perhaps the most beautiful effects are produced 

 when the shadow-producing body is in the shape of a 

 flat ring, placed a short distance from the bottom of the 



