DiiCEMBER 5. 1907] 



NA TURE 



115: 



ations should be undertaken at once under the control of 

 thp department of geophysics of the University of Naples 

 pending the formation of the geophysical institution 

 which is to be established at Pozzuoli, and that Govern- 

 ment assistance should bo asked for the necessary means 

 of carrying on the temporary researches rendered urgent 

 by tlie present eruption. Prof. Bassani, in conjunction 

 with Dr. A. Galdieri, describes further observations on the 

 windows broken at Ottajano during the eruption of 

 Vesuvius of 1906, and maintains their view, which has 

 been doubted by other writers, that the damage was 

 done by lapilli driven against the windows by the action 

 of wind. 



"The Climate of Abbassia, near Cairo," is the title of 

 No. 3 of the useful Survey Department papers now 

 being issued by the Egyptian Ministry of Finance. The 

 observatory at Abbassia was founded by the Khedive 

 Ismail Pasha in 1868, and was removed to Helwan in 

 1903. Summaries of the observations have been issued 

 from time to time, except for the five years before the 

 removal ; the present report contains a careful discussion, 

 by Mr. B. F. E. Keeling, of the results of those five years 

 and summaries of the mean values for the whole thirty- 

 five years. The mean annual temperature was 70°.2 ; 

 January, 54°- 1 ; July, 83°.5 ; the absolute extremes, ii7°.i 

 (August, 1881) and 28°-4 (February, 1880). Rainfall js 

 very small; the mean for seventeen years was only i-iS 

 inches ; from June to September, inclusive, no rain falls. 

 There are about 3100 hours of bright sunshine annually, 

 not far from double the average amount in the south of 

 England. Series of charts show the mean annual and 

 daily curves for each of the principal elements. 



We have recently had an opportunity of inspecting and 

 testing the binocular diffraction spectroscope patented and 

 sold by Dr. Marshall Watts, and have found it to be a 

 remarkably efficient instrument for the spectroscopic in- 

 vestigation of light-sources of definite form, such as 

 vacuum tubes. It consists of an ordinary good field-glass 

 having attached in front of each object-glass a trans- 

 parent diffraction grating mounted on optically worked 

 plane glass. In examining a luminous vacuum tube we 

 found that the bright lines apparently stood out in relief, 

 whilst the illumination, even in the second and third 

 orders, was verj' satisfactory. The first-order spectrum of 

 Capella, on by no means a perfect night, was seen as 

 quite a bright colour band. For the examination of 

 broader light-sources, such as flames or arcs, a metal or 

 ebonite plate with a slit in it may be usefully employed in 

 order to obtain a purer spectrum. The price of the 

 binocular spectroscope is 3?. 35., and further details of 

 the instrument may be obtained from Dr. Watts, 

 " Shirley," Venner Road, Sydenham. 



The fortieth anniversary of the existence of the German 

 Chemical Society was celebrated recently in Berlin. We 

 learn from the Times that the meeting was devoted to 

 retrospective addresses on important achievements of chem- 

 istry during the last fortv years. Prof. Nernst delivered 

 an address on physical chemistry ; Prof. Landolt spoke on 

 the development of inorganic chemistry ; Prof. Graebe de- 

 scribed the successes of the chemistry of the carbon com- 

 pounds by the process of synthetical combinations ; and 

 Prof. Otto N. Witt, who discussed the development of 

 technical chemistry, remarked that technical chemistry has 

 brought about a revolution in productive industry mainly 

 by the aid of electrotechnical science. Prof. Witt directed 

 attention to the manufacture of cellulose from wood lead- 

 ing to the changed methods in the production of paper, 

 to the employment of nitro-cellulose for the preparation of 



NO. 1988, VOL. yy] 



silk-like substances for weaving, to the synthetic produc- 

 tion of indigo and alizarin, and to the fixation of atmo- 

 spheric nitrogen. 



The current number of the Oxford and Cambridge 

 Review, the second issue, contains two articles dealing 

 with scientific subjects. Mr. J. Butler Burke contributes 

 an article on " Haeckel and Haeckelism," and the head- 

 master of Eton College, under the title " More about Bio- 

 metry," tells of the introduction of the system of anthropo- 

 metric measurement of the boys at Eton, and refers to this 

 movement as " a united act of faith in the desirability ol' 

 knowledge for its own sake." 



A SECOND edition, which has been revised and enlarged, 

 of " The Practice of Soft Cheesemaking : a Guide to the 

 Manufacture of Soft Cheese and Preparation of Cream 

 for Market," by Messrs. C. W. Walker-Tisdale and 

 Theodore R. Robinson, has been published by Mr. John 

 North at the office of the Dairy World and British Dairy 

 Farmer. The characteristics of the book were described 

 in a review of the first edition which appeared in Nature- 

 for June 9, 1904 (vol. Ixx., p. 137). The practice of 

 making soft cheese is increasing in this country, and this 

 new edition of a useful book should assist small holders 

 endeavouring to gain a livelihood from the land. 



OUR ASTRONOMICAL COLUMN. 



Mercury as a Morning Star. — Although the present 

 elongation of Mercury — the planet was at greatest western 

 elongation (20° 20') at 2h. on Sunday last — is not so 

 favourabje for the naked-eye observation of the planet as 

 those which took place in February and August re- 

 spectively, there is a possibility that during the next day 

 or two observers may be able to pjck up this elusive 

 object near the eastern horizon just before dawn. On 

 December 6 the planet will rise at c,h. S7m. a.m., the" 

 sun at 7h. 51m., whilst on December 8 the respective 

 times will be 6h. 4m. and 7h. S4m. 



At this season of the year an object near the horizon 

 is not easy to find, and the would-be observer would do 

 well to learn beforehand the exact rising point, and then 



Relative positions of Mercury and bright stars at 6 a.m. December 6 ; 

 observer facing due east, 



to get into such a position that the horizon thereabouts 

 is quite free. The planet rises a little less than 30° S. 

 of E., and this direction may be noted, and in some way 

 marked, on the previous evening, by observing the rise 

 of Sirius, which takes place in the same azimuth at about 

 9 p.m. /3 Librae rises about an hour before Mercury at 

 a point some 15° nearer the east point. 



The accompanying rough sketch-map may assist the 

 observer to locate the planet. It is intended to show the 

 approximate position of the stars, with the observer facing 

 due east, at the time that Mercury rises, the stars being 

 shown here as projected on to a plane parallel to the plane 

 of the meridian. 



A Bright Meteor. — An exceptionally bright meteor was 

 observed bv Mr. T. F. Connolly, at South Kensington, at 



