844 



NATURE 



1)1 



-S, 192 



of caneit in which the ixostatic anomaUcs suggest 

 ilccidtxl <lcparturcM from isKMtatic cquiUbrium can be 

 reaMonably acioiintfd for bv what may In? regarded 

 aa a second approximation lo the fart* ; th«» simple 

 Hayfordian theory is that the codm i*s» 



or defect of density is diHtribute<i un :^h- 



out a cohimn of a certain depth, in'icjxri'icnt of 

 locality. Prof. Ik>wie has shown that in many cases 

 there is geological evidence for the fxistence of 

 heavier or lighter hkIcs (as the case mav be) nearer 

 the surface, and that these are capable of accounting 

 for many of the anomalies referred to, without sup- 

 posing the isostatic compensation to be incomplete. 



Carbonisation of Coal. — The Fuel Research 

 Board has issued a report (Technical Paper No. 8) on 

 " The Steaming of Wigan .\rlev Coal in Vertical Gas 

 Retorts " (M.M.S.O.. ^4. net). It sets out the 

 results which were obtained when this particular coal 

 was carbonised with gradually increasing quantities 

 of steam in the (ilover-VVest vertical retorts of the 

 Fuel Research J3oard's experimental station at 

 Xireenwich. The coal is one largely used for gas- 

 making in Lancashire, and the tests on it were carried 

 out " at the request of the Preston Gas Company, the 

 Wigan Coal and Iron Company, Ltd., and Messrs. 

 West's Gas Improvement Company, Ltd., these firms 

 combining to bear the cost of 300 tons of coal for the 

 purpose." A large amount of detail as to the results 

 obtained finds its place in the text of the report, and 

 particularly in tables given at the end, from which 

 It is plain that an attempt has been made to secure 

 as much information as possible during the tests for 

 the guidance of gas engineers who may be thinking 

 of using this coal. It is interesting to note that some 

 data have been accjuired for the fuel consumption, as 

 reported thus : " The amount of heat required per 

 ton for the carbonisation of this coal, including the 

 sensible heat in the products, varied from 13-0 therms 

 with 5 per cent, steam to 18-25 therms with 20 per 

 <:ent. steam. The intermediate points were not 

 obtainable owing to the amount of heat which was 

 taken up by the setting when only three retorts were 

 in use being unknown." 



Temperaturk-measuring Instruments. — A use- 

 ful l)ooklet of 71 pages has been issued by the 

 Cambridge and Paul Instrument Company, in which 

 a concise account is given of the various temperature- 

 measuring instruments made by this firm. A perusal 

 of its contents shows that the number of useful 

 devices applicable to the measurement of temperature 

 is continually increasing, so that the user has now 

 a much wider choice than heretofore. Descriptions 

 are given of dial and index thermometers, the latter 

 being provided with an electric alarm attachment 

 for ringing a bell when the temperature differs from 

 that at which it is desired to work. With both these 

 types continuous records may be taken on charts 

 by means of a moving pen. In connexion with 

 platinum resistance thermometers, direct-reading 

 mdicators for any assigned range are provided, in 

 which the movements of the pointer depend upon 

 the extent to which a Wheatstone bridge is thrown 

 out of balance by the var\-ing resistance of the 

 platinum at different temperatures. Thermo-electric 

 pyrometers, with base-metal and rare-metal couples 

 and suitable indicators and recorders, are described ; 

 a form used for measuring surface temperatures, and 

 methods of cold-junction control, being of special 

 interest. Amongst radiation and optical pyrometers, 

 a description is given of a recent pattern of the 

 ■disappearing filament type, capable of reading to 

 2100° C. A new feature is the introduction of 

 •devices for the automatic control of temperatures, 

 ■either of gas or electric furnaces or tanks of liquids. 



NO. 2823, VOL. I 12] 



Control is efjcctctl ffum lUc uKhcator by m< 

 relay, which comes mto action when the 

 teni; is reached, and operates a metaa-i. 



will tcs the supply from the source of h- • 



Thf in^ii iimunts described under this head rep-^ 



distinct advance in temperature-measuring ap, 



"F'ishing" in Om.-weul Drii-linc;. — li 

 a term employc<l bv the driller to cover an. 

 of different operations connected with the Urii) .; 

 of oil-wells, but it is invariably synonymous with 

 trouble of some kind or other, and always calls for 

 the greatest skill and ingenuity on the part of the 

 operators concerned. Technically speaking, the pro- 

 cesses of side-tracking of tools, casing, or sinniar 

 obstruction, frequently necessary in env--"-"' <• 

 come within the purview of " fishing 

 recovery of lost or " stuck " tooN r 

 broken ropes or rods, lost or bi 

 removal of " frozen " pipe or other < , 



the drilling of the well — these are some of the manv 

 kinds of trouble experienced by the driller. Fishmt^ 

 methods differ with the -type of drilling system in 

 vogue, with the efficiency of the drilling crew, and 

 to a large extent according to the country in whi( h 

 the oil-field is situated. It should l>e borne in mind 

 that operations of this character are usually lengthy, 

 tedious, and expensive, since while they are beinj; 

 carried out the weH certainly cannot be 

 any money ; consequently producers are 1 

 more and more alive, to the necessity for n-'iui v..-^ 

 fishing operations to the absolute minimum, by tin- 

 employment of the most skilful drillers, equipped 

 with the most up-to-date tools and devices for 

 achieving the desired results. Drilling is becoming 

 more and more of a science, less of routine manual 

 labour; it is therefore valuable to have the adv;int a-. ^A 

 a paper such as Mr. Albert Millar's, read on N 

 13 before the Institute of Petroleum Tech; 

 dealing with the Galician-Canadian pole tool nshing 

 methods, which provided a natural sequel to his previ- 

 ous paper on the same system of drilling for petroleum. 



Mercury as a Working Substance for Binary 

 Fluid Turbines. — The possibilities of the use of 

 mercury in this connexion were discussed in a paf>er 

 read by Mr. William J. Kearton before the Institu- 

 tion of Mechanical Engineers on November 16. No 

 fluid exists which possesses the ideal conditions for a 

 single fluid turbine ; hence the use of two fluids — one 

 having a high boiling-point to be used in a hmh- 

 temperature turbine, and the other with a low boilmj.;- 

 point to be used in a low-temperature turbine. Mercun.- 

 may be used for the first fluid and steam for the 

 second. It is stated that an experimental mercurv-- 

 vapour turbine has been built in the United States by 

 the General Electric Company to the designs of Mr. 

 Emmett, and that a second turbine has recently been 

 put into operation. There does not appear to be any 

 published information on the subject in Great Britain. 

 A considerable amount of experimental work has Ix-en 

 done by chemists and physicists on the propertio of 

 mercury, but all the data required for a complete 

 study of the problem are not at hand. A lartje 

 amount of research work, particularly in connexion 

 with the determination of latent heats at high tem- 

 peratures, remains to be done. A considerable part 

 of Mr. Kearton 's paper is taken up with a discussion 

 of the properties of mercur\', and the results obtained 

 by many workers are rev-iew-ed. The author has 

 calculated tables giving the relation of temperature, 

 vapour pressure, sensible heat, latent heat, total heat, 

 entropies of the liquid, of evaporation, and of the 

 mercury vapour ; these tables appear in the paper, 

 and are supplemented by diagrams showing the 

 properties graphically. 



