July 5, 1888] 



NATURE 



227 



The low, ill-defined cumulus in Mr. Hook's " Low-Tide 

 Gleanings " are not more finished than the rest of the 

 picture, but are correct both in form and drawing ; and 

 the same remarks apply to his work, " A Day for the 

 Lighthouse." 



" Thanet Cliffs in the Time of Peace," by Mr. S. Cooper, 

 shows a good cumulus with cirrus overhead ; but in Mr. 

 C. Hunter's "Fishers of the North Sea" the cumulus 

 cloud is not satisfactory. 



Mists on a mountain, with a gray sky, are very well 

 painted in Mr. Faed's " And with the Burden of Many 

 Years," and make an effective background to a striking 

 work of art ; while in " The Approach to Bealloch-na-ba " 

 Mr. H. Davis has delineated mountain mist with equally 

 good effect. 



Mr. P. Graham's "A Norfolk River" contains a very 

 good showery sky, but the brush-marks give an app earance 

 of fibrous structure which would not be in Nature ; while 

 his "Driven by the Wind" contains an effective mass of 

 gray nimbus or rain-cloud. 



Mr. W. Shaw paints a good misty yellow-tinted sky in 

 his " Tide Race" ; but the great mass of cumulus behind 

 Sir F. Leighton's central figure of the "Captive Andro- 

 mache" is not very satisfactory. 



The sky in " The Old Water-Way," by T. Liddell, is 

 good so far as form is concerned, but is painted so heavily 

 that the clouds look like clods. Philologists say that the 

 word cloud is really derived from clod, but artists should 

 not express that idea in their works. There is a rainbow 

 in this picture, so ill defined that it is difficult to make 

 out the succession of tints ; though I think the red is 

 meant to be outside, which is correct. 



Mr. R. Rouse's " Pasture-land in Kent " would be much 

 more pleasing if the clouds were more carefully painted, 

 and not so like patches on the sky. In No. 553, Mr. H. 

 Wells is to be complimented on having painted rays 

 diverging from the sun from exactly the proper kind of 

 sky. These rays are rarely seen except through a peculiar, 

 flat, broken cloud ; but they are usually associated with a 

 firmer, harder sky than is here depicted. 



Lastly, Mr. C. Johnson paints the " Plain of Arundel " 

 under two well-drawn layers of cloud ; and Mr. J. 

 MacWhirter has hit off with great skill and accuracy a 

 flat, broken cloud, lit from below by a setting sun, beside 

 the picturesque castle of " Edinburgh." 



Such are some of the more notable skies in our great 

 national exhibition of pictures, and it will be seen at once 

 that the best skies are painted as a rule by those who 

 have achieved the greatest success in the other elements 

 which make up a good picture. May we not therefore 

 fairly conclude that part of their success is due to their 

 faithful rendering of skies and clouds ; and that it behoves 

 those who wish to attain a high place among landscape 

 painters to study the form, the structure, and the perspec- 

 tive of those clouds which give life, and height, and 

 distance, to every picture ? Ralph Abercromby. 



THE OXFORD UNIVERSITY OBSERVATORY. 



'THE following are the principal parts of the Thirteenth 

 ■*■ Annual Report of the Savilian Professor of Astronomy 

 to the Board of Visitors of the University Observatory, 

 read June 6, 1888 : — 



I. Lectures. — In addition to the requisite statutable 

 lectures, Prof. Pritchard has offered some others of a 

 more elementary and quasi public character on descrip- 

 tive astronomy, and expressed as far as possible in un- 

 technical language. He has been so much encouraged by 

 the interest manifested in these lectures that he proposes 

 to offer another and perhaps more extended series on the 

 recent speculations as to the origin of the Cosmos from 

 meteoric collision and on matters cognate therewith. 



II. Instruments. — The De La Rue equatorial is in 

 excellent order ; its mechanical mounting is now equal 

 to the delicate purposes of stellar parallax to which it has 

 been uninterruptedly applied during the last twelve months. 

 Although the mirror is perhaps somewhat dimmed with 

 age, its figure, which has been recently tested by com- 

 parison with the presumed best productions of the day, 

 retains its original very remarkable character. 



The two mirrors mentioned in the last Report have 

 been mounted temporarily on the large equatorial for the 

 purpose of the comparison of their photographic action. 

 An efficient electric control contrived by Sir H. Grubb 

 has also been added with the view of securing the great 

 accuracy necessary in the movement of the telescope. 

 The work for which the mirrors were intended having 

 been completed, they have now been dismounted. 



Dr. De La Rue having provided the funds necessary 

 for a photographic telescope of 13 inches aperture and of 

 the pattern suggested at the Paris Conference of 1887, 

 the large equatorial has been sent to Sir H. Grubb at 

 Dublin, for the purpose of attaching thereto the instru- 

 ment in question, and of carrying out the other con- 

 siderable alterations necessary for the photographic 

 charting of the heavens, as proposed at the aforesaid 

 Conference. 



The transit-circle is in perfect order. 



III. Buildings. — Mr. Nasmyth has presented his 

 magnificent picture map of the moon for the service of 

 the Observatory. This very beautiful work of art (6 

 feet in diameter) was completed by Mr. Nasmyth from 

 actual observation with a large telescope of his own 

 construction in 1849. 



IV. Astronomical Work. — During the past year this 

 has been twofold. In the first place continuous attention 

 has been devoted to the photography of small portions of 

 the heavens with the view of determining the parallax of 

 certain selected stars. In the first instance a careful trial 

 of the method was made on the parallax of 61 1 and 61 2 

 Cygni, because the parallax of the point midway between 

 the two stars had been determined, with presumedly 

 great accuracy, by Bessel in 1838, whereby effective means 

 of comparing the two methods were supplied. The 

 general agreement of the result obtained from photo- 

 graphy with that determined by this most able astronomer, 

 together with the remarkable consistency of the individual 

 photographic measurements, satisfied Prof. Pritchard not 

 only of the great convenience, but also of the unimpeach- 

 able accuracy of the method. Dr. Pritchard has conse- 

 quently much extended these operations for stellar parallax, 

 and before the termination of the presentyear he hopes that 

 the computation of the parallaxes of altogether some ten or 

 twelve stars will be completed. The list will comprise 

 61 1 and 61 2 Cygni, /* Cassiopeia?, and Polaris, which four 

 stars may be regarded as already completed. Three 

 more parallaxes have been provisionally determined from 

 observations of six months* viz. a. 0, y Cassiopeia? ; four 

 others also are in a forward state. Experience has 

 suggested that these stellar parallaxes will be most readily 

 and efficiently determined by confining the photographic 

 work on each star to those four periods of the year which, 

 in respect of each parallactic ellipse, are the most effective 

 for the purpose. It should be stated that for the purposes 

 of accuracy four stars of comparison are selected, instead 

 of the two with which astronomers have hitherto been 

 generally contented. This photographic process enables 

 Prof. Pritchard also, without much consumption of time, to 

 measure from night to night the distance between the stars 

 of comparison themselves, thus furnishing a check to the 

 unavoidable variability of the scale of the focal field and 

 of the photographic film. These operations are at present 

 restricted to a systematic catalogue of stars of the second 

 magnitude. It appears that astronomical work like this 

 is well adapted to an Observatory connected with a great 



