November 8, 191 7] 



NATURE 



185 



some decompositions of protein, although Kell- 

 ner's investigations indicate that the animal does 

 not benefit thereby. The decomposition by bacteria 

 is prevented in the stomach by the hydrochloric 

 acid of the gastric juice, and in the lower part of 

 the large intestine by the progressive resorption of 

 water from the intestinal contents. In the small 

 intestine, however, the organisms are more active, 

 giving rise to ammonia, phenols, indols, etc. The 

 two latter are largely resorbed ; they are of little, 

 if any, use to the animal — indeed, they are 

 poisonous ; they combine, however, with other sub- 

 stances and are excreted in the urine as the so- 

 called ether-sulphates. 



Considerable progress has been made in our 



[knowledge of the utilisation of fat. At an early 



[stage in the mobilisation of the reserve in the adi- 



)se-tissue cells the fat becomes hydrolysed, yield- 



ig glycerol, which, perhaps, serves as a source of 



Mextrose, and a fatty acid, which is oxidised. Dakin 



Land others have shown that the oxidation of the 



jid begins at the jS carbon atom {i.e. at the second 



)m the COOH group), and results in the splitting 



of two carbon atoms at a time, yielding water, 



irbon dioxide, and another fatty acid containing 



iro fewer carbon atoms than the original one, with 



rhich the same process of erosion is repeated. It 



IS not yet clear, however, how the animal utilises 



rmic, acetic, and propionic acids, although it 



idoubtedly does so. 



The author then proceeds to discuss the various 



^rpes of experiments made by investigators in 



inimal nutrition : the simple feeding trial, in which 



gross gain in body-weight is measured for 



particular ration ; the digestibility experiment, 



rhich requires more careful measurement and aims 



determining what proportions of the various 



constituents have been digested and resorbed ; 



"balance experiment," in which respiration 



'terminations are added to the foregoing in order 



make up a balance-sheet showing exactly what 



»as become of the food ; and, finally, the elaborate 



calorimeter experiment, in which an attempt is 



made to trace the energy changes involved. 



The author is well known for his investigations 

 on the energy relationships of nutrition, and his 

 own beautiful calorimeter at State College is the 

 envy of many another institution. He devotes 

 considerable space to this aspect of the subject. 



Incidentally, he makes an interesting comparison 

 between the efficiency of a horse and that of a 

 power plant. He finds the total useful work done 

 by a working horse was 2*8 therms ; the gross 

 energy of the ration was 55*8; the over-all effi- 

 ciency was, therefore, 5*1 per cent. The animal 

 worked six hours per day. Supposing his bodily 

 machinery was stopped for the other eighteen hours 

 (as an engine would be), and he was charged with 

 only a fourth of his maintenance requirement, the 

 over-all efficiency would be raised to 6*3 per cent. 

 ■ — about that of a modern American locomotive. In 

 actual practice the conditions with an animal are 

 very much as if it were necessary to keep up a full ; 

 head of steam for twenty-four hours, or to run an 

 NO. 2506, VOL. 100] 



internal-combustion motor continuously, although 

 work is only done for part of the time. 



The author attaches less importance than usual 

 to starch equivalents, which he considers may 

 obscure the energy relationships. Altogether the 

 volume is very interesting, and will be read by 

 agricultural teachers with much pleasure. 



ULUGH BEG'S CATALOGUE OF STARS. 



Ulugh Beg's Catalogue of Stars, revised from all 



Persian manuscripts existing in Great Britain, 



with a vocabulary of Persian and Ara:bic words. 



By E. B. Knobel. Pp. 109. {Washington : 



Carnegie Institution, 1917.) Price 2 dollars. 



HP HIS work forms a sequel to Mr. Knobel's 



■*- edition of Ptolemy's Catalogue (see Nature, 



vol. xcvii., p. 282). Owing to the war he has 



only been able to use codices existing in England, 



but these are fortunately rather numerous, and 



twenty-two Persian and Arabic MSS. have been 



collated. A partial collation of three Persian 



MSS. at Paris by the late Prof. C. H. F. Peters 



has also been utilised. 



This catalogue of 1018 stars, the first original 

 catalogue since that of Ptolemy, is founded on 

 observations made during the reign of Ulugh Beg, 

 a grandson of Tamerlane, at his observatory near 

 Samarkand, the epoch being a.d. 1437. It was 

 published in 1665 by Hyde from three codices at 

 Oxford, and this edition was reprinted in 1767 in 

 the collected edition of Hyde's works. It was again 

 issued by Baily in 1843 in his edition of ancient 

 star-catalogues, in which the stars were for the first 

 time identified and the modern designations given, 

 Mr. Knobel's edition differs from Hyde's not only 

 by being founded on a far greater number of 

 codices, but also by giving the places of the stars 

 for 1437 computed from modern star-catalogues 

 (by Peters) and a comparison of these with Ulugh 

 Beg's places. 



No particulars about the instruments employed 

 or the methods of observing are known. Peters 

 was the first to notice that the minutes of the 

 longitudes are generally of the form 3/1+ i, while 

 the minutes of latitudes are multiples of 3, as if 

 the circles of the instrument were graduated to 3' 

 and some correction of i', 4', or 7' had been 

 applied to the longitudes. Ulugh Beg states that 

 twenty-seven stars in Ptolemy's Catalogue were 

 too far south to be observed at Samarkand, and 

 that their places were, therefore, borrowed from 

 Ptolemy, allowance being made for precession. 

 Mr. Knobel has found that the longitudes of four 

 other stars were derived in the same way, and 

 were not observed. In addition to these, there 

 are at least eighty-two pairs of stars of which 

 the longitude of one star only was observed, while 

 that of the other (a few degrees distant) was 

 obtained by adding or subtracting Ptolemy's 

 difference of longitude. The latitudes of sixty- 

 eight stars were simply copied from Ptolemy, 

 and there are at least forty-four pairs 



