December 21, 1893] 



NA TURE 



183 





National Museum. In it is given a systematic description o 

 tjie species of the hymenopterous family Proctotrypid^c found 

 north of Mexico ; the genera of the world being also studied and 

 described, as an aid to future students. The Proctotrypidae 

 are considered by some authorities to be closely allied to the 

 Chalcididce, which they usually follow in catalogues and lists of 

 hymenopterous families. Mr. Ashmead considers, however, 

 that there is little affinity between the two, and that such an 

 arrangement is unnatural. He thinks that the Proctotrypidse 

 should be placed at the head of the Terebrantia, for after the 

 removal of the group Mymarince (which probably forms a 

 separate and distinct family allied to the Chalcididte), there 

 is no relationship with the Chalcidida;. 



The first volume of " Studies from the Physical and Chemical 

 Laboratories" of the Owens College has been published, 

 and it furnishes evidence of the large number of important 

 investigations carried on by the alumni of the College. The 

 volume contains thirty papers in all, most of which have been 

 reprinted from the Transactions and Proceedings of various 

 societies. A paper by Mr. J. A. Harker, "On the Reaction of 

 Hydrogen with Chlorine and Oxygen," has been translated 

 from the Zeitschrift filr Physicalische Cheniie, and appears in 

 English for the first time. Among the papers not previously 

 published is one "On New Forms of Stereometers," by Mr. 

 Haldane Gee and Dr. Harden, and another " On the Duration 

 of Chemical Action in the Explosive Combination of Gases," by 

 Dr. Turpin. The council of the Owens College has done a good 

 work by collecting and publishing the results of researches 

 made in its laboratories during the last few years. 



In his paper on the " Glacial Striae in Somerville," Mr. 

 Upham concludes, from a large series of observations, "that 

 the currents of the ice-sheet were deflected here from one course 

 to another, and even to several sixccessive courses in so short a 

 time that it allowed no great amount of erosion of the rock 

 beneath." The general motion of the ice-sheet during the period 

 of its maximum thickness was south-south-east over the Boston 

 area, but it was deflected eastward during the recession of the 

 ice. The long axes of the drumlins have also an eastward 

 direction, and Mr. Upham finds in this fact evidence that they 

 were formed wholly during the time of deflected glacial move- 

 ments. 



Since the publication, in 1868, of Pasteur's classical work, 

 " Etudes sur le vinaigre," the only contributions of importance 

 to this subject are those made in this country by Mr. Adrian 

 Brown. It is, therefore, interesting to learn that Dr. Lafar 

 intends devoting special attention to the whole question of the 

 fermentation of vinegar, and the Centralhlatt Jilr Baateriologie, 

 vol. xiii. p. 684, 1893, contains his first contribution to, as well 

 as a short review of, the existing literature on this important 

 subject. In the course of his researches at the Institute for the 

 Experimental Investigation of Fermentation Industries near 

 Stuttgart, Dr. Lafar obtained a species of yeast which rendered 

 beer strongly acid, and on studying its behaviour in other 

 alcoholic media it was found to produce vinegar. The various 

 observations made with this interesting organism are con- 

 veniently brought together in a table, and include the determin- 

 ation of the amount of vinegar produced, the changes, both in 

 taste and smell, induced in the media, the formation of surface- 

 film, &c. In his next communication, Dr. Lafar hopes to furnish 

 more exact particulars of the physiological and bacteriological 

 characters of this vinegar- producing yeast. 



The Illustrated ArcluvologistioxTiQZQvcAitxcoviizX'Cil, a number 

 of very fine illustrations. Among the articles is one " On the 

 Excavation of a Pictish Tower in Shetland," by Mr. G. Goudie. 

 The author thinks that the remarkable round towers with the 

 remains of which the islands of Orkney and Shetland are studded 

 MO. 1260, VOL. 49I 



may be assigned a date as far back as the commencement of the 

 Christian era, or earlier. Mr. Arthur Elliot writes on " Some 

 Old Towers at Liege," and Mr. J. Romilly Allen, "On the 

 Celtic Brooch, and how it was Worn." Dr. R. Munro contri- 

 butes some notes on flint saws and sickles, in which he discusses 

 the diff"erences between Egyptian sickles and the saws found 

 in the Polado lake-dwelling near Desenzano. He is of the 

 opinion that there is little or no evidence that such sickles were 

 in use among the prehistoric people of Western Europe, though 

 compound saws of the kind discovered at Polado may be found 

 among the (/c'Z'r/j of prehistoric civilisations beyond that of the 

 lake dwellings of Europe. 



The additions to the Zoological Society's Gardens during 

 the past week include a Macaque Monkey {Macacus cynomolgus) 

 from India, presented by Sir F. D. Dixon-Hartland, Bt., M.P. ; 

 a Ring-tailed Coati {Nastia riifa) from South America, pre- 

 sented by Mr. Kenelm Chandler; two Arctic Foxes {Cams 

 lagopus) from the Arctic Regions, presented by the Duke 

 of Hamilton, K.T. ; a Red Kangaroo iMacropus rufus) 

 from Australia, two Short-toed Eagles {Circatus gallicus) 

 European, deposited ; a Moloch Lizard {Moloch horridus) from 

 Australia, presented by Mr. John Carter. 



In line four of article " Experiments on Flying " (Nature. 

 December 14), read n\ instead of 7^ . 



OUR ASTRONOMICAL COLUMN. 



Colour-x\berration of Refracting Telescopes. — At 

 a recent meeting before the Royal Astronomical Society, 

 the proceedings of which will be found in the Observatory 

 (No. 208, December), Mr. H. Dennis Taylor read an abstract 

 of a paper entitled " The Secondary Colour-Aberration of Re- 

 fracting Telescopes in Relation to Vision," which had for its 

 aim ihe determination of the detriment to vision, if any, and 

 the percentage of light lost for defining purposes, owing to the 

 presence of the usual colour-aberrations. In the colour curves 

 which the author exhibited, where the wave-lengths and longitu- 

 dinal colour-aberrations were represented by the ordinatesand ab- 

 scissise respectively, some remarkable facts were brought to light. 

 A comparison with Captain Abney's curves of the luminous in- 

 tensity of the normal solar spectrum gave a means of obtaining 

 a rough estimate of the percentage of light thus lost. The 

 following table gives one a rough idea of these losses for different 

 objectives in the case of star work, 100 representing the whole 

 amount of light transmitted : — 



Objective. Focal length. Ljght lost. 



36-inch Lick Telescope ... 57 ... 27 



24 ,, Refractor ... ... 30 ... 42 



12 ,, „ 15 • • 21 



6 „ „ 74 ■•■ 9 



28 ,, Greenwich Refractor ... 28 ... 50 



Other conclusions which the author draws from the above inquiry 

 may be stated as follows:— In large telescopes the light-gathering 

 power for star work by no means increases as the square of the 

 aperture, the focal length being constant, but a point is reached 

 when it increases simply as the aperture. With a given large 

 aperture the light -grasping power can be considerably augmented 

 by increasing the focal length. In the case of large telescopes, 

 a smaller telescope of relatively large fecal length may actually 

 excel in light-grasping power a telescope of larger aperture and 

 shorter focal length. In his concluding remarks Mr. Dennis 

 Taylor refers to the increase of size in the images of stars under in- 

 creasing exposures ; this, he says, can be accounted for by the 

 photographingofthebaloof wasted light which surrounds the real 

 image. If further research corroborates the views above stated, 

 there seems to be no doubt that there is still room for improve- 

 ment in rendering our lenses more perfectly achromatic. Of 

 course the main point in large telescopes is to have them as 

 short as possible, and it is satisfactory to notice the comparative 

 smallness of the light lost in the 36-inch Lick instrument. 



Stars with Remarkable Spectra. — The present list {Astr. 

 Nach. No. 3200) is a continuation of that which appearedin a 

 previous number of the same journal {Astr. Nach. No. 3171). 



