226 Chronicles of Science. [April, 



hood of the radiant point the paths of meteors, heing foreshortened, 

 would be reduced to mere points; secondly, the paths of all the meteors 

 produced backwards would indicate by their common intersection 

 near a single point the existence and position of the radiant centre. 

 Most of our best observers obtained satisfactory evidence of both 

 sorts; all recognized the latter phenomenon. In the figure the 

 results of nine sets of observations have been recorded : — The small 

 cross marked (1) indicates the radiant point determined by Mr. 

 Alexander Herschel ; (2) we have deduced from the map of the 

 Greenwich observers ; (3) marks two crosses — the upper Mr. Hind's, 

 the lower Sir J. Herschel's determination ; (4) is Mr. Pritchard's ; 

 (5) Professor Grant's ; (6) Professor Adams's ; (7) marks two 

 crosses — the upper Professor Challis's determination, the lower Mr. 

 BaxendelTs. Mr. Herschel quotes ten other results, some of which 

 we have omitted, as appearing to be the results of less exact obser- 

 vation ; others, because there was no space for them in our figure. 

 For instance, Mr. Penrose's determination coincides almost exactly 

 with Professor Grant's. 



Mr. Maclear, who observed the shower at the Eoyal Observatory, 

 Cape of Good Hope, considers that the radiant point was nearer 

 Eegulus than ^, and about y, but he did not particularly note its 

 position. 



On one point the above evidence seems decisive. The meteors, 

 at the time of our encountering them, were neither crossing the 

 earth's orbit from without inwards, nor from within outwards, by an 

 appreciable angle. In the figure, the cross on the Ecliptic indicates 

 the point on the celestial sphere towards which the earth was 

 travelling at the moment of encounter — or, more exactly, the 

 point towards which we in England were being carried by the 

 combined effects of the earth's revolution and rotation. The 

 dotted line indicates the longitude-circle through this point (which 

 has been called the " apex of the earth's way "). Now, the fact that 

 the radiant point lies in the neighbourhood of this point at all, shows 

 that we meet the meteor-zone ; the fact that the radiant-point lies about 

 10° to the north (along the dotted line) shows that the zone crosses 

 the earth's orbit from the north southwards, at an angle greater than 

 10°,* or, as it is technically expressed, that the meteors are at their 

 descending node, when we encounter them. If the radiant-point 

 had lain to the left of the dotted line, the fact would have shown 

 that the zone crossed our orbit from within outwards — that is, that 



* If we travel northwards against a rain-shower blown southwards, we are met 

 more fully by the shower than if we are at rest ; in other words, the shower seems 

 to come from a point lower down towards the north : the amount of change 

 depends on our velocity. Assuming the meteors' velocity not to differ greatly 

 from the earth's (a probable assumption, as we shall see presently), the angle of 

 10° indicates a true inclination not differing greatly from 20°. Professor Newton's 

 theory that the period of the meteors is 354 days, would make the angle about 19°. 



