July 12, 1917] 



NATURE 



385 



^ble condition, which is not in use, and is willing 

 to part with it for work of national importance at 

 a reasonable price, I should be glad to hear from 

 him the particulars as to type, condition, and price 

 "desired. When the war is over machines will return 

 to their normal price — indeed, will probably, be at 

 reduced prices, for the war has taught many persons 

 their value, and the market will be wider than it has 

 hitherto been, so that foreign monopolies are certain 

 to be broken down. Karl Pearson. 



Department of Applied Statistics, University 

 College, University of London, July 5. 



The Hippocampus in Ancient Art. 



Reproductions of early figures of the common 

 Mediterranean species of Hippocampus have been pub- 

 lished by Prof. Raymond Osburn in the Zoological 

 Bulletin for March, 1915, and also by the present 

 writer in the annual report of the Smithsonian Insti- 

 tution for the same year. 



It is remarked in the latter of these articles that no 

 mention is found in Aristotle of this striking form of 

 fish-life, and the term " Hippocampus" was used by the 

 poets of classical antiquity as the name of a sea 

 monster, half-horse and half-fish, on which sea divini- 

 ties rode. Nevertheless, the design of the seahorse 

 occurs not infrequently in the plastic arts of Hellenistic 

 civilisation, both in Greece and in Italy. The seahorse 

 IS figured occasionally also among the island gems, as 

 stated by Fiirtwangler, who figures one of them 

 {Antike Gemtnen, vol. i., pi. v.). 



Figures of animals, including fishes, represented in 



ancient Grecian 

 vase paintings have 

 been made the 

 subject of special 

 study by a young 

 French artist, 

 Morin-Jean,^ and a 

 compatriot of his, 

 P. H. Boussac, has 

 written interesting 

 articles on fish de- 

 signs inscribed in 

 ancient Egyptian 

 monuments.^ 



Only one instance is known where the Hippocampus 

 Is depicted in ancie.nt works of art from the Nile valley. 

 The design referred to forms part of a decorative 

 painting in the interior of a mummy-case dating from 

 the Twenty-sixth Dynasty (700-500 B.C.), now preserved 

 in the City Museum of Gloucester. A brief description 

 of it is given in vol. ii. of the "Historical Studies" 

 published by the British School of Archaeology in 

 Egypt, and this is accompanied by a photograph of the 

 original, which we have copied in the annexed figure. 

 Certain of the details are thus indicated in the de- 

 scription just referred to:— "The greater part of the 

 Hippocampus is outlined in black on the white ground 

 of the coffin ; the ears, the eyes, the nostril, and the 

 mane [i.e. conventionalised dorsal fin] are indicated in 

 black ; round the jaw is a wide black band edged with 

 yellow ; the muzzle is yellow with black dots ; the wide 

 horizontal stripes on the neck are alternately blue and 

 -'" edged wnth black. . . . The date of the coffin 



^ 



J> 



Fig. I. — Hippocampus, from an Egyptian 

 mummy-case, c. 500 B.C. 



red 



accords well with the period of the archaic Athenian 

 pediments." C. R. Eastman. 



.American Museum of Natural History, 

 New York. 



1 '• Le dessin des animaux en Grece, d'apres les vases peints." Po. 262 

 illustrated. (Paris, 1911.) ' 



- _" Les poi^sons sur les monuments pharaoniqaes," Le Naiuraliste vols. 

 XXXI. and xxxii. (1909-10). ' 



NO. 2489, VOL. 99] 



THE HUNDRED-INCH REFLECTOR OF 

 THE MOUNT WILSON OBSERVATORY. 



"D Y the courtesy of Prof. Hale we are able to 

 -L' reproduce the accompanying- interesting" 

 photographs relating to the giant reflector of the 

 Mt. Wilson Observatory, which is now rapidly 

 approaching completion. 



The history of this great telescope dates from 

 1906, when Mr. John D. Hooker, of Los Angeles, 

 presented the sum of 45,000 dollars to the Carnegie 

 Institution for the purchase of a glass disc and 

 to meet other expenses incident to the construction 

 of a loo-in. mirror for a reflecting telescope of 

 50 ft. focal length. In making this gift, Mr. 

 Hooker was well aware that the construction of 

 such an instrument was to be regarded as an 

 experiment, but in view of the great possibilities 

 in astrophysical research which a large reflector 

 seemed to oft'er, the experiment was considered 

 to be well worth making. No insuperable diffi- 

 culty was anticipated in the casting of a suitable 

 disc by the French Plate Glass Company, of St. 

 Gobain, and there was every reason for confidence 

 in Mr. Ritchey's ability to grind and figure the 

 mirror to the highest pitch of perfection. Expe- 

 rience already gained with the 60-in. telescope also 

 gave confidence that the mounting of the larger 

 instrument could be successfully accomplished. 



Although no financial provision was made for 

 the mounting and housing of the proposed tele- 

 scope, Mr. Hooker's gift was accepted, in the 

 confident belief that in due course a donor would 

 be forthcoming. 



An order for the disc was accordingly placed in 

 the autumn of 1906, and the building in which the 

 grinding, figuring, and testing of the mirror were 

 to be carried on was erected during the following 

 winter. In 1908 Prof. Hale reported that a disc 

 had been successfully cast, but in the following 

 year it was stated that on its arrival in California 

 the disc exhibited many defects, and had been im- 

 mediately rejected. The makers generously ex- 

 pressed their willingness to bear the loss and to 

 make a further attempt. A large furnace and melt- 

 ing-pot capable of holding twenty tons of material 

 were constructed ^ and improved methods of anneal- 

 ing were introduced. Early in 1910 another large 

 disc was successfully cast, but owing to defects in 

 the mould, strains were set up during annealing, 

 and the disc was broken. 



In view of this disappointment it was resolved 

 to make a trial of the disc which had previously 

 been laid aside, and grinding was commenced in 

 the autumn of 1910, Meanwhile, further attempts 

 to cast a disc free from flaws and bubbles were 

 made, but a^ain, owing to difficulties of anneal- 

 ing, a second disc was fractured in the oven. In 

 the course of these trials, however, a flawless disc 

 of the necessary diameter was produced, but its 

 thickness was only 8 in., and this was not con- 

 sidered adequate to prevent deformation, unless a 

 very perfect system of supports could be devised. 



Mr. Hooker, unfortunately, did not live to wit- 

 ness any progress beyond this stage, having died 

 on May 24, 191 1. 



