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NA TURE 



319 



research and speculation, it was in tracing the history of 

 the younger formations that he did his best work and 

 spent the chief part of his scientific career. Since the 

 year 1864 he has been unweariedly engaged in investi- 

 gating trie history of the Pliocene and Post-pliocene 

 deposits of the East of England. Taking up this subject 

 in conjunction with Mr. Harman, he soon became con- 

 vinced that no satisfactory progress could be made in it 

 until the deposits in question had been actually mapped 

 in some detail. Accordingly the two observers began to 

 trace them on the one-inch Ordnance Map, Mr. Wood 

 taking the southern half of the area, including Essex and 

 nearly the whole of Suffolk. This survey, which for 

 minuteness and accuracy has seldom been equalled by 

 the work of any private workers, remains unpublished, 

 though a reduction of it, on the scale of four miles to an 

 inch, was issued in 1872. Mr. Wood eventually gave up 

 his business, which was that of a solicitor, in order to 

 devote himself with more uninterrupted zeal to the prose- 

 cution of his favourite science. The bodily feebleness 

 which debarred him from much active work out of doors 

 seemed only to quicken his energy for literary labours. 

 Some of the best fruits of his life-long devotion were 

 gathered into his two long memoirs on " The Newer 

 Pliocene Period in England," published in 18S0 and 1882 

 by the Geological Society. But his friends anticipated 

 much useful work still to come from one who had pursued 

 his studies with such intelligence and zeal, and who had 

 only reached his prime. In his death, at the age of fifty- 

 four, they mourn one who was ever ready cheerfully and 

 helpfully to impart to others the knowledge he possessed 

 himself, who never hesitated to admit an error when he 

 recognised it, and who leaves behind him a notable 

 example of quiet fortitude and enthusiasm. 



A SUXSHIXE RECORDER 

 /^\N June 28 of last year I had the honour of bringing 

 ^— before the Physical Society a preliminary notice of 

 a new sunshine recorder,' and as we have now had more 

 than six months' experience of its working, it is possible 

 that some of your readers might be interested in hearing 

 of the results obtained. 



The apparatus is of simple construction. It consists 

 of a glass sphere silvered inside and placed before 

 the lens of a camera, the axis of the instrument being 

 placed parallel to the polar axis of the earth. The 

 whole arrangement will be readily understood by an in- 

 spection of Fig. 1. The light from the sun is reflected 

 from the globe, and some of it, passing through the lens, 

 forms an image on a piece of prepared paper within the 

 camera. In consequence of the rotation of the earth, the 

 image describes an arc of a circle on the paper, and when 

 the sun is obscured, this arc is necessarily discontinuous. 

 The image is not a point, but a line, and in certain 

 relative positions of the sphere, lens, and paper, the line 

 is radial and very thin, so that the obscuration of the sun 

 for only one minute is indicated by a weakening of the 

 image. 



In the actual apparatus the sphere is an ordinary 

 round-bottomed flask about 95 mm. in diameter, and the 

 lens a simple double convex lens of about 90 mm. focal 

 length. The sensitive paper employed is the ordinary 

 ferro-prussiate paper now so much used by engineers for 

 copying tracings. This was selected in consequence of 

 the ease with which the impression is fixed, for the paper 

 merely requires to be washed in a stream of water for six 

 minutes, no chemicals being necessarv. When the paper 

 is dry, radial lines containing between them angles of 15^ 

 ire drawn from the centre of the circular impression, 

 and thus give the hour scale, the time of apparent noon 

 being of course given by a line passing through the plane 

 of the meridian. Fig. 2 is a copy of the record of June 



' Prvc. Phyi p . I4! . 



27, 1884 ; in the morning the sun shone brightly, towards 

 noon clouds began to form, and in the afternoon the sky 

 was hazy. The field in which the instrument is placed is 



surrounded by trees, so the ends of the ttace are cut oft 

 sharply by shadows. 



With the alteration of declination of the sun, the light 



entering the camera is reflected from different portions of 

 the sphere, and an alteration of the position of the focus 

 results. This may be corrected in three ways : by moving 



