s^. V ^. \\ i^ ^ IMAGE EVALUATION TEST TARGET (MT-3) ^ 1.0 1 1.1 s la nzo &5iri!si^ 4§o CIHM/ICMH Series. CIHM/ICMH Collection de mi Canadian Inatituta for Hiatorical Micrcraproductiona / Inatitut Canadian da mibroreproductiona liiatoriquas Technical and Bibliooraphic Notaa/Notaa taohniquaa at bibliographlquaa to The Inatituta haa attamptad to obtain tha baat original copy avaiiabia for filming. Faaturaa of thia copy which may ba bibliographioaHy uniqua. which may aKar any of tha imagaa in tha raproduction, or which may aignificantly changa tha uaiiai mathod of filming, ara chackad balow. □ Colourad covara/ Couvartura da coulaur rn Covara damagad/ n Couvartura andommugte Covara raatorad and/or laminatad/ Couvartura raataurAa at/ou paiiiculAa □ Covar titia miaaing/ La titra da couvartura manqua lourad mapa/ Cartaa gtegraphiquaa wi coulaur Colourad inic (i.a. othar than blua Encra da coulaur (i.a. autra qua blaua ou noira) I I Colourad mapa/ I I Colourad inic (i.a. othar than blua or black)/ r~n Colourad piataa and/or iliuatrationa/ D D D Pianchaa at/ou iliuatrationa an coulaur Bound with othar matarial/ Rali4 avac d'autraa documanta Tight binding may cauaa aliadowa or diatortion along intarior margin/ Laraiiura aarrte paut cauaar da I'ombra ou da la diatortion la long da la marga intiriaura BIttnk iaavaa addad during raatoration may appaar within tha taxt. Whanavar poaalbla. thaaa hava baan omittad from filming/ II aa paut qua cartainaa ivagaa Manchoa oloutiaa lora d'una raatauration apparaiaaani dana la taxta, maia, loraqua cala Atait poaalbla, caa pagaa n'ont paa 4ti f iimtea. Additional commanta:/ Commantairaa aupplAmantairaa: L'Inatitut a microfilm* la maillaur axamplaira qu1l lui a At* poaalbla da aa proourar. Laa dAtaila da cat axamplaira qui aont paut-Atra unlquaa du point da vua bibiiographiqua. qui pauvant modiflar una imaga raprodulta, ou qui pauvant axigar una modiflcatiof^ dana la mithoda normala da f ilmaga aont indiquia ci-daaaoua. D D D a D D D D D Colourad pagaa/ Pagaa da coulaur Pagaa damagad/ Pagaa andommagAaa Pagaa raatorad and/c r laminatad/ Pagaa raat&uriaa ot/ou pailiculAaa Pagaa diacoiourad, atainad or foxad/ Pagaa dAcoiorAaa. tachatiaa ou piquiaa Pagaa datachad/ Pagaa dAtachAaa Showthrough/ Tranaparanca Quality of print variaa/ Qualit* inigal* ^ I'impraaaion Includaa aupplamantary matarial/ Comprand du material auppMmantaira Only adition avaiiabia/ Saula MKIon diaponibia Pagaa wholly or partially obacurad by arrata alipa. tiaauaa. ate., hava baan rafiimad to anaura tha baat p;.«aibla imaga/ Laa pagaa totalamant ou partlaHamant obacurclaa par un fauillat d'arrata. una palura, ate. ont AtA film4aa A nouvaau da fa^on i obtanir la maWaura Imaga poaaiMa. Th po of fHv OffI bai th« aio oti fin aio or I ahi Tin wh Ma difl Thia itam la filmad at tha raduotton ratio chackad balow/ Co documant aat film* au taux da iMuctton in-^^ ir . March 1894. proposed Corrections to the Measure of Time. 287 •5» >-93 •36 •46 10 reoeive a oorreotion of i* 36 in oonseqnenoe of the alleged change in the sidereal time at mean noon. The claim that this correction starts from zero aboat 1864*0, and increases uniformly at the rate of about 1**48 annually, is based by Mr. Stone on the fact that that was the date when Le Verrier's tables were introduced into the Nautical Almanni',, and when, in consequence, according to Mr. Stone's theory, the new measure of time began. Now, to show my difficulty, let us suppose that the old tables of the Sun had been continued up to the end of the year 1891, and that in the year 1892 Le Verrier's Tables had for the first time been introduced. To make my meaning perfectly clear I shall call the case of actual introduction in 1864, case A; and the supposed case of introduction in the year 1892, case B. On Mr. Stone's theory, the time t should in case B be counted from 1892*0, and the correction therefore for 1892 January 6 would have been substantially zero. But it is evident that the tabular numbers for the whole year 1892, and therefore for January 6, would have been exactly the same in case B as they are in case A ; that is to soy, if tho solar ephemeris from Le Verrier's Tables had been computed foi the first time for the year 1892, all the quantities taken from the tables and printed in the Nautical Almanac would have been the same as they actually are. To claim that they would have been different would imply that the results of making a computation from Le Verrier's Tables are not merely a function of the numbers contained in the tables, but of the time when they began to be used for the ephemeris of the Nautical Almanac. Were this doctrine true it might also be possible thai the quantities taken out from a table of logarithms were different from year to year. As this cannot be the case it conclusively follows that all the numbers used in computing the tabular place of the Moon at transit over the meridian of Oxford on 1892 January 6 would be ertactly the same in case B that they are in case A. Consequently the result would have been the same as Mr. Stone gives it for the nncoi-rected time ; that is to say, we should have had — Observed Bight Ascension of the Moon ... R.A. from Hansen Tables for uncorrected M.T. Hansen minus observed uncorrected Correction due to the change of unit in M.T. Hansen minus observed corrected 49 I9S7 20-93 + 136 000 + 1*36 out ght ,rd, ^ate Thus Mr. Stone's theory and his method of npulying it giva a correction zero for 18940 in case B, when in fact the numbers to be corrected are the same- as they are in case A. From this conclusion I see no escape From Mr. Stone's theory the use of the new unit of time would, in ca«e B, have commenced in 1894. a88 Prof, Newcomhy Uemarha ef<'.. uv. 5. Here / must be reokonod from 18940, and tlie correction munt b» zero. Tims liis thcorjr gives two iucunHiHteiit correct ions to the Hanie numbers. SiiolUtirouile ± Co. Prinleri, X-ir-xIrrrl Si/imie, Lviidon. mmm