12 



KNOWLEDGE, 



[January, 1904. 



Point of radiation. loD^ + 22^°. 



Character of meteovr--, bright generally, with streaks 

 and swift motions. 

 Several Leonids and meteors belonging to contemporary 

 minor showers were doubly observed, and their real paths 

 have been computed. Among the latter there was a 

 Taurid fireball, seen on November 16, about loh. 42m.. at 

 Enniscorthy and Lisburn. It passed over the S.E part of 

 . Anglesea at heights from 72 to 32 miles, with a velocity oF 

 23 miles per second. Radiant at 61 + 24^ A 2ud 

 magnitude meteor appeared on November 15, loh. 59m.. 

 directed from a radiant at 113° — 34^ and descending 

 from 64 to 48 miles along an extended course of about 142 

 miles from over Sussex to Lincoln. Velocity about 19 miles 

 per second, but the flight of the meteor seemed much 

 retarded by atmospheric resistance, and at the end of its 

 visible career, as observed at Bristol, it became almost 

 stationary, its material and momentum being apparently 

 quite exhausted. 



Hcttrrg. 



[The Editors do not hold themselves responsible for the opinions 

 or statements of correspondents] 



> 



LARGE VERSUS Sil.lLL TELESCOPES IX 

 PLANETARY WORK. 



TO THE EDITORS OF KNOWLEDGE. 



Sirs, — In the course of his interesting article on Saturn 

 in the current number of Knowledge, Mr. W. F. Denning 

 has referred to the well-known fact of large telescopes 

 sometimes failing to show faint planetary markings that 

 were visible in those of much smaller aperture. The 

 mirkings in question usually appear to be those having a 

 considerable apparent area and a more or less diffuse and 

 indefinite outline, and I do not remember to have ever 

 seen anv demonstration, either theoretical or practical, why 

 markings of this nature sh'juld be any jdainer or better 

 seen as a whole in a large telescope than in a small one. 

 As regards minute details there can, however, be no 

 question as to the superiority of the large telescope. 



But my present object in writiuor is to draw attention 

 to the fact that the remarkal)le and instructive experi- 

 ments on artificial markings, details of which have been 

 recently published, seem to have an intimate bearing also 

 on this question of the failure of large telescopes to show 

 planetarv- markings visible in smaller ones. Particulars 

 of one of these experiments having a special bearing on 

 the sul)ject, made by Mr. and Mrs. Maunder, have been 

 recently published in the Journal of the British Astrono- 

 mical Association, Yol. XIIL, page 349. In this experi- 

 ment two waved parallel lines when viewed at a distance 

 of 130 feet, gave rise to the appearaace of a faint, diffused 

 t)and. On approaching nearer, the experimenters found, 

 to their evident surprise, that this appearance after awhile 

 began to get feeble, and finally disappeared aUoijether at a 

 distance of about 100 feet. Nothing could then be seen 

 at the place of the two waved hues until approach had 

 been made to very nearly 60 feet, when the lines rapidly 

 became distinct. 



Now the employment of a larger aperture, and probably 

 higher power, woidd no doubt be analogous in its effect to 

 a diminution in the distance of the object, and hence, even 

 assuming all other things to be equal, it does not seem 

 diflicult to conceive the existence of a jiarticular kind of 

 mai-king that would give rise to a distinct irapressiim in a 

 small telescope, although nothing whatever could be seen 

 at the same place with a large one. For instance, a number 

 of faint, irregular, naiTow streaks crossing the bright 



equatorial zone of Saturn, perhaps analogous in their 

 nature to the well-known equatorial "wisps" of Jupiter, 

 and corresponding to the waved lines of the experimeut, 

 might give rise to an appearance of alternate faint and 

 dark areas or spots in a small telescope, though a " giant" 

 telescope might fail to show anything whatever of this 

 ap]:iearance. Yet such apparent markings or spots, 

 although not strictly objective, would clearly have an 

 objective basis, and heuce they would be suitable for 

 determining the rotation period. 



A. Stanley Williams. 

 Hove. 10 j3, December 1. 



THE ORCHID CEPHA.LANTBERA GRANDIPLORA. 



TO TBE EDITORS OF KNOWLEDGE. 



Sirs, — I have long had a thing to say about the 

 fertilization of Cephilaufhera yrandifiora. and now that 

 Mr. Praeger's hiterestinij article on Orchids has appearei 

 dim't think I could fit it with a better time. 



Figs. 1 and 2 represent respectively the front and side 

 views of the column of this plant, and are drawn from life. 

 What are the threads that cross and re-cross and attach 

 themselves not ouly to the stigma but to the front of the 

 column and sides of basal portion of labellum, like the 

 supporting strands of a spider's web r IE they are pollen 



Fig. 1. 



Fig. 2, 



tubes, why the cui-ious reticulation ? At first I thought 

 the meshes were caused by pollen grains falling upon 

 different parts of the column, whence they might germinate 

 in any direction, but, in spite of Darwin, who says the 

 grains " readily adhere to any object," I have tried to 

 remove thein at all stages of development and not one 

 grain could I get away, not even with the hairy edge of a 

 piece of blotting paper ; now I am thinking that the 

 earliest tiilies as they elongate may drag out and carry 

 down from the poUinia grains that may be later in 

 germinating, and would thus add meshes to the net. How 

 does my supposition stand ': I should add that pollen 

 masses almost entirely disappear when the threads are 

 most numerous. 



24, Iffley Road, C. E. Clark. 



Hammersmith, W., 



November 16th, 1903. 



