June 17, 1920] 



NATURE 



495 



.differences. The authors arrive at the generalisation 

 that resolution of the bands on cooling depends on 

 the existence of regular crystalline structure; as an 

 example of this, the broad bands observed in uranium 

 glass are not further resolved on cooling to the tem- 

 perature of liquid air. It is shown that many of the 

 apparent shifts of the bands with change of tempera- 

 ture are to be referred to the relative enhancement 

 or diminution of the components of the bands. A 

 <iiscussion of different types of phosphoroscope is 

 included as an appendix. 



The May lecture of the Institute of Metals on. 

 ■ Recent Progress in Thermo-EIectricity " was de- 

 livered by Prof. C. A. F. Benedicks, of Stockholm 

 University, on June lo, Engineer Vice-Admiral Sir 

 ■George Goodwin, president, in the chair. Prof. 

 Benedicks first gave a short summary of his 

 theoretical views upon the metallic conduction of 

 electricity. A consequence of this theory was 

 that one has to conclude that even in a single 

 homogeneous metal thermo-electric currents do 

 occur, and not only when two different metals 

 are pwesent. Prof. Benedicks gave a concise 

 demonstration of the most important experimental 

 ^jvldence of the truth of this conclusion, utilising for 

 this purpose various metals. In liquid mercury it had 

 been possible for him definitely to prove the existence 

 of thermo-electric currents, thus disproving the nega- 

 tive results of previous workers. A consequence of 

 what the lecturer termed his ''homogeneous thermo- 

 electric effect " was that there must exist the reverse 

 effect, the "homogeneous electro-thermic effect," in- 

 cluding as a special case the well-known Thomson 

 effect. The reality of this effect was duly made clear. 

 A specially interesting demonstration was of a new 

 rotating thermo-electric apparatus made entirely of 

 copper and rotating in a magnetic field, the driving 

 ' force originating solely from unequal heating (by 

 means of a tiny gas jet) of thin strips of copper. The 

 point at which the new knowledge brought forward 

 by Prof. Benedicks might have some practical interest 

 lay in the possibility of reducing the thermal con- 

 ductivity of metals by insulated subdivision into fine 

 wires without impairing the electrical conductivity. 

 The demonstrations were carried out with the aid of 

 a galvanometer kindly provided by the Cambridge and 

 Priul Instrument Co. 



Drs. a. Harden and S. S. Zilva, continuing their 

 •work on accessory food substances, publish in the 

 Biochemical journal for April a paper entitled " The 

 Antiscorbutic Requirerhents of the Monkey." The 

 authors point out that as the clinical syr^ptoms of 

 scurvy induced in the monkey are similar to those 

 pccurring in human subjects suffering from a similar 

 disease, the monkey has been more and more exten- 

 sively empliDyed as an experirhental animal. On the 

 other ■ hand, comparative scarcity, high price, and 

 greater duration, of experiment render the mohkeV 

 in many instahpes less suitable than the guinea-pig 

 for the study of experimental scurvy, in order to trans- 

 late results" obtainefd with one animal into the 

 NO. 2642, VOL. 105] 



terms of the other Drs. Harden and Zilva havft 

 attempted to establish a quantitative relatiqnsl^ip, as 

 regards dose and time, between them. In the wprk 

 described five monkeys fed on a scorbutic diet of 

 rice, wheat germ, salt mixture, and butter receivjed 

 respectively 0-5 c.c, 075 c.c, i c.c, 2 g.c, and 5 c.c. 

 respectively of orange juice daily. The animals re- 

 ceiving only 05 c.c. or 075 c.c. developed scurvy wfith 

 fatal results, whilst the one receiving i c.c. only 

 suffered from a mild attack, and in the cases of 

 2 c.c. and 5 c.c. doses the animals remained quite 

 healthy. The authors conclude that the minimum 

 daily dose of fresh orange juice for a monkey (weigh- 

 ing 2-3 kilos.) is 1-2 c.c, which is approximately 

 the amount required by a guinea-pig weighing 300^400 

 grams. Whilst, however, the minimum dose of 

 antiscorbutic required by the two animals is of the 

 same order, the disease develops in the guinea-pig 

 in three weeks, but only after two months in the 

 monkey. 



In pursuance of his campaign for recognition as a 

 pioneer inventor of oil engine cycles, we have received 

 a number ot documents from Mr. Herbert Akroyd 

 Stuart, formerly an assistant at Finsbury TecHnical 

 College and now of Claremont, in Western Australia. 

 One type of Mr. Stuart's engines has been manufac- 

 tured on a large scale by Messrs. Hornsby, of Gran- 

 tham. The cycle in this engine is carried out in a 

 cylinder fitted with a hot 'bulb, the walls of which are 

 kept hot during ordinary working by the heat de- 

 veloped during explosion. Air is drawn into tlrc cylin- 

 der through a side-port in front of the bulb, and oil 

 fuel injected into the bulb during the suction stroke. 

 Compression follows, and at the end of this stroke 

 ignition takes place due to the temperature developed 

 by the hot walls and by the compression. Mr. Stuart's 

 other cycle has not been worked commercially to any 

 extent. It also is carried out in a hot-bulb cylinder, 

 and consists in drawing in air only during the suc- 

 tion stroke, compression of this air, and injection of oil 

 fuel into the bulb during the early part of the working 

 stroke, the temperature being then sufficient to cause 

 the oil to burn readily. Both these cycles were in- 

 vented in 1890. Mr. Stuart objects, and rightly so, to the 

 name "semi-Diesel " being applied to engines working 

 on these cycles. He has first claim as the inventor of 

 hot-bulb engines, and the term "Akroyd cyclfe '* 

 would be suitable. The Diesel engine proper has no 

 hot bulb ; air alone is compressed to a very high pres- 

 sure (500 lb. per sq. in.), and the temperature due to 

 compression alone is sufficient to ignite the oil fuel 

 which is injected during the early part of th^ Working 

 stroke. The tdrrrt " Diesel engine " might continue to 

 be used for such engines. The high pressures used in 

 the Diesel engine and the extensive use of the engine 

 for marine purposes gave rise t6 a diemand' for an 

 engine working with lower pressures, arid the" pa'St 

 few years have seen a great development ip hot-bulb 

 engines. Someone acquainted with Diesel engiries and 

 probably unaware of Mr. Stuart's prior work named 

 these " serini-Diesel," a term .which may. very well be 

 dropped in favour of ' Akroyd engines, if onlv tp|C tfie 

 sake of historical accuracv. ■ -• 



