330 'MONTHLY WEATHER REVIEW. AUQUBT,1900 these are smaller ranges, viz : the Massanutton Mountain, 3e done. The present discussion is, therefore, devoted to this Powell's Mountain, Three-Top Mountain, and others. Sky- 3na. land is so located on the west slope of the Blue Ridge, near Following a suggestion from the editor of the REVIEW,the Stony Man Mountain, that it has immediately on its west work of each observer concerned has been reduced independ- the gap called Newmarket Gap, near the southern end of ?ntly and the results given in Table 1. The fact that the Massanutton Mountain. To the west of this the line of sight wiginal records were prepared by different observers, at dif- passes over the hills of the southern end of the ridge of North Ferent times, with different instruments dift'erently exposed, Mountains and strikes the Shenandoah range of mountains. renders this procedure necessary in order to avoid fallacions The upper part of the valley of the Shenandoah River lies results. Perhaps the materials supplied from these various between the Blue Ridge on the east and the Shenandoah 3ou.rces can be reduced to a homogeiieoas system of normal Mountains on the west. values. Mr. C'ragin adds: Referring to Table 1, it will tie observed that there are four Many of the thunderstorms in the Shenandoah Vallev seem to be livisions, each presenting the means by hours as obtained what are called " valley " storms in Professor Davis's Meteorology, From the con~pilationsof the observer indicated at the head caused by ascending hot air in the way he speaks of, and not of much Df the division. At the head of the first division is the name 61 ength. 3f George James Evelyn, to whoni much praise is due for his long and patient labors, extending over a period of tweuty- seven years (from 1856 to 1182, inclusive), and for his kind- ness in permitting the exclusive use of the same for publica- tion in the MONTHLYWEATHER REVIEW. hlr. Evelyn came to St. Kitts sixty-nine years ago and, although nom a nona- genarian, is still in the enjoyment of excellent health and a youthful spirit, his greatest impediment being, apparently, defective eyesight. The writer has more than once listened with pleasnre to his reminiscences of the distant past. - He \vas receiver-general or subtreasurer for the colony during the time he made his nieteorological observations and did this work of his own accord in addition to his official duties. The barometer used by hIr. Evelyn helonged to the govern- ment and was presumed to be a good one; it was one of the fixed cistern manufactured by J. Nixon, London. The tube of this barometer is smaller than the tubes of the barometers used hy the Weather Bureau and is encased in a wooden frame, to which is attached a metal scale and vernier. It was esposecl in an east room, on the ground floor of the treasiiry building, being attached to the partition wall on the west side of the rooni, and was not, perhaps, more than 12 feet above sea level. It was not moved during the whole series. The readings were made by simply adjusting the vernier and observing the figures then indicated. Mr. Evelyn is positive that 110 corrections were applied to the readinge, hence it would appear that unless the manfacturer, by some method of calibration, made compensation for instrumental errors, and it seems he did, these readings may be consider- ably out. Inasmuch, however, as this error, whatever it may he, is constant, or nearly so throughout, there is a compara- tive value in the results which ought not to be overlooked. Attention is invited to the explanatory note under Table 1. This table upon a cursory or superficial inspection may ap- pear to he erroneous in view of the well-known diurnal baro- metric changes. Under normal conditions in all tropical rpgions the barometer rises from 4 a. m. to 10 a.m., and falls from 10 a. m. to 4 p. m., and so on. Mr. Evelyn's observa- tions apparently run contrary to this recognized principle, 8s is seen by comparing the 8 a. m. mean, for instance, with the CLIMATOLOGY OF ST. KITTS, W.I. 9 a. 111. or 10 a. m.mean. Eut this is evidently fallacious for reasons which will appear from a study of the note just re- By W. S ALEAANI,EIC,Observer. Weather Bureau, dated Bugurt 77,1900, ferred to. If now we compare the 8 a. m. mean with the 12 A paper containing certain descriptive and tabulated datn noon and 4 p. m. means, as is manifestly proper, we find that relative to this subject was published in t,he MONTHLI they are in accord with this principle. For instance, the WEATHERRERIEW, Annual Summary, 1899, and some addi. January mean for 8 a. m. is 30.015; for 12 noon, 30.025; and tional details in the February, 1900, REVIEW. The fact that for 4 p. m., 80.017. The February mean for 8 a. m. is 30.019; these meteorological data cover a period of forty-four yearE for 12 noon, 30.033 ; and the 4 p. ni., 30.016, and so on, just seems to justify, if, indeed, it does not demand, a more ex. as the principle would lead ne to expect. So, also, the 9 a. m. tended discussion. It appears to be important, in order tc means may be compared with the 3 p. m. means and the same arrive at the true and full value of these old records as well relation is ohserved. The same is true of the 10 a. m. and 2 as of the service performed by the compilers of the same p. m. means, with possibly one exception, namely, the means that a statement in detail be made of the conditions anc for February. Here we find the 10 a. in. mean less than the agencies involved in the original records, so far as can nov 2 p. m., whereas we should expect the reverse. The first

Unauthenticated | Downloaded 09/28/21 02:58 AM UTC AUGUEJT,1900. MONTHLY WEATHER REVIEW. 33 1

ESPLANATCIRT.

Local time. which is forty-njlle minutes fa:ter than seveut.y-fiftli meridian. is used throiiehont.. escept by the Unit.ed States Weather Bureau. The figures, in .( thesis just Iielow the headinns Baro." and Ther." indicate the number OF years upou which the me.qo is based. A.'Erely?r'r rec01t7.-1. The 8 a. m. the I2 noon, and the 4 p. m. readings were made froni 1558 lo lb67 incnlusive-ten years. 2. The 4 a ni. readings were made from le69 to ItW. inclusive-foiirteen years.' 8. The 10 a.in.readings were made in IYSi, lS57, aud Iwj?-three year;. 4. The 2 p. m.readiugs were mide from 1Stiu to 188%,iiicluslve- eleven years. B. Hnneock'a ?eeord.-l. The 9 a. m. readings mere made from lS92 t.0 1SAI. inclllrire-three years. 2. The 10 a. m. readiugs were made from 1893 to 18%. inclnsire-three pears. 3. The 3 p. m readings mere made froiii 1x93 to lR!li, iiiclusire-air pears. C'. t'lngeninn'r ieeovd.-The readings werw madw at 9 n. m. and 3 p. in. frRDm January tn November. inclusive, 1 u. Th.e Ikiled Nfnlef Il'enlher E.frren7r wmrd.-l. The R a m and 8 ~'.ni.rraflinv.ilwrcnty-fifth mrridiau tinier were made from March. 1899. to February. I'JW-one year. The readings fa,r January and February, l9pO. were used iustrad of those fur IbY9. Iwcause the observations were made at 6 a. 111. and 6 p. m. during those months in I&IQ. 2. The 1;' noon means are taken from the Richard barograph for IR!I!L. It will be ObSerred that these hourly m~ausare baaed tipon the means uf cvusecutire years with one exceptloii, the 10 a. in. meau. The thermometric mean8 are for very nearly the same year3 an the barometric. In general. the barometric means are Ixlieved to hold gooil for rea level.

cj d,rection': No. miles. ~__ P.m. Per 1 Per day. I hour.

1892.

January...... ' 29.984',' 78.9 74.7 ~ 74.6 73. 8 78.4 87 22 70 5t 71 Fehruary ...... 29 990' 78.3 71.4 , 71.Odl 89.8 70.4 77.1.. ~ RS 2Bt 68 2nt 04 March ...... EO. i 76.8 ' 75.7" 8.5.3 72.0 iP.6 90 4t 68 41 74 April...... SO. 6 75.8 ' 75.04 W.6 72.4 iP.0 86 lot; 70 It "-73 May ...... 30 017- 82.0 78.9 77.8'' 84.3 74.4 i9.1 89 20 71 9t June ...... 30'0tiOc1 84.6 81.2 ' M.7c! 87.0 75.6 81.3 89 30 71 20 79 July...... 30.056 30.019e: 85.6 88. i 85.4.1 89.1 1 75.5 31 72 22 I 81 August...... 3O.M)B 29.968' 86.4 84.2 8.5.1 f' 89.9 i1. 6 19 71 23 83 .sei

December .... ~ 29: 9d 29.9500 81.0 74.6 74.1e1 84.3 I 71.6 7x0 80 5t 69 ?It 70 11198. I J~nuary..... 29.991 29.968' 81.4 78. 0 2i 67 10 69 CW Pebrurry .... .i 30.02; , OY.993' 80.9 I1.W., 3 66 9 08 March ...... 30.013 ' 29 989. 79.8 ""I,.+ ,, 6t 61; 11 t 66 April ...... 80 00." 29:970*' R0.3 78.3 It 66 12 68 May ...... 29:981*' 29.962dI 81.8 i9.9 in.. 711 14 72 June...... 3O.W 39.99df' 85.2 81.1 St, fo 9 i3 July...... 29.075 ' 29.95i'l 88.4 81.6 an 70 5 .-atr August ...... 29. 946 29.9l2?, 8ti.D 53.0 31 72 Nit 76 Swl,t,ember.. ..I ...... October ...... "9 (H5b, 29.919" 85.4 83.71' 79.11 7S.O' 88.0, 73.9, 31.0 15 70i 30 79 November ....I i9:865 29.8lr 84.6 83.06: 77.3 76.2g~88.1 I 72.4 80.2 9 fi8 30 75 December .... 2y.W~ 29.Y16-' 80.1 80.1' 74.0 $4.03, 83.9 71.4 77.6 9!! S 68 21 79 1uw. ,January ...... I 29.9% 29.9648 78.8 79.66 72.6 76. I 85 29t 65 22 68 68%...... 3.37.'. 14.0 Fwbruary ..... ; 30.019 30.010hl 78.7 60.4h 71.9' 76.6 Hli 17 66' 10 67 67" ...... 361 15.0 March ...... 30.0d7 29.9HRf, 80.1 81.lf 71.3 i6.3 8i lot 62 71 67 6Yf ...... 305 19.7 April ...... 30.00:j w.oc 74.8 78.2 90 15 66 15 70 71...... ' ...... 1254 '!.$ Map ...... P9.954 84.8' 78.1 81.2 9'2 28 71 It 7s 73' ...... 1 ...... ~.1%~ I ,., June ...... 30.043 85.3' 78.1 81.8 92 16 72 3 73 ...... l 281 11.7 July...... 30.055 86.2C 78.0 R-?. 0 9' 25 72 4 73 ...... , 347 14.5 August...... 80.005 87.OC 78.6 82. 8 92 10 7% 2.21 i4 ...... 2s7 12.0 Septeiirher ..... 29.966 86.iC 79.4 82. 4 91 17 72 3t I 75 ...... m 8.5 Oct. 3ber ...... 29.958 85.2'I 78.6 79.8 91 I 12 69 21 74 ...... Noverntier ..... 29.967 87.3e 77.4 90 3 69 6 74 73' ...... I...... December .... P9.949 29.9Mh~ 81.1 R1.8b~ 75.6 I,., 68 21 64 28 72 ?'hi ...... ~ ...... 9n.m. 9 a.m. 19 a.m. 9 a.m. 19 a.m. , 9a.m. to 9 a.m. 29.957. 3.3 76.8 81 64 1'2 1 69 ene. 292 12.2 29.965. 79 9 77. 4 18 66 10t 6s e* 2i4 11.4 29.979' 80.4 $8.8 ?9+ 68 1 68 e. hy n.? 3'27 13.6 Aprll ...... 30.022 20.9tii' 81.5 R.'. 0 22 73 2t z7 e. bys.fl 953 10.5 May ...... 30.012 P9.9W 82.2 79.4 15 70 24 '* 77' e. by 6. e.e 309 12.9 June ...... 30.043 30.08f 83.6 8.2.2 5t 73 2; 74.. 73' e. e.f 297 14.0 Juiy...... I 30.027 ?o.Oold 89.8 8'. 4 9 73 lot, 75 76' e. e.* 371 15,s August, ...... I 29.943 .zY.B~L~I 86.4 82.7 29 73 3tl r' $8' e. e.' 2961 12. 8 Ye 111ember.. .. 29.99 I %9.901~ 82.9 83.0 13 70 30 (1 77* e. bye. e: 259 10.8 October ...... 29.939 29 865" 86.7 81.6 10 71 25 ~ 77 Rld e by6. e.d Ili 8.0 November .... 29.9.U 29:We' 81.3 80.4 2 68 3 i4 e. by s. e : 280 11.7 29.888s 79.7 78.3 14 04 19 ~ 73 778 e. by 8. e. hy s.1~ 208 8. 7

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TABLET-Showing means for ceTtain hours and yews, together with other dicta--C'oiitinueil.

__ p~- I Temperature (Fahrenheit). I I Wind. Air pressure ~ Dew-poiut. 1 Re'atir0 (in iuchesl . , humidity. Prevailing Average Dry- Wet. Mean. 1 1 Date. I 1 ci direction. I No. miles.

~ ~ -i I 1 Max Min. ~ Ql * .-Eb* day.per 1I hour.Per 10 a. m 3 p.m. loa m 3p.m. E

~~ ~ - p~ __ , 1 1886. cc c l,., 75.3" 84.6 70.6 77.6 87 ti5 "9 I 71 January ..... :9.975 29.947' 81.5' 73.5 2,8 February.. .. -9.989 29 981' 78.8 81.7' 73.3 44.8.' 84.2 i".9 77.6 87 8 ti7 70 Ytlrch ...... 29.980 29.945' 79.0 82.S' 73.4 74.9~ 85.6 70.2 77.9 88 7 63 :' 70 April ...... 29.987 29 9311 80.6 81.19 74.7 76.0s 88.7 72.4 79.6 89 25 70 20 i0 May ...... 29.953 29.931 82.9 85 8K 77.7 79.lK 88.1 74.6 81.4 9.2 31 71 21 i4 June ...... 30 003 29.977' a.3 &.4* 78.8 79.30 88.8 75.7 82.2 91 21 72 1: ;ti e.l~y11.c 326 13.6 July 30.015 29.996' 83.5 85.5n i9.6 80.5' 88.6 7ti.0 90 O"t $'2 It c- e.,l 3119 12.9 ...... 82.3 rr. 29. !M6' 85. 86.9' 80.3 80.1' 90.5 76.4 83.4 93 29 e:! e. f r;3 11.4 August ...... 29.975 n r" 29.8% 86.5 88.5d 80.8 81.8' 91.4 75.4 95 10 $2 Et I!. ' 217 9.0 Srptember ... 29.931 a.4 rl October ...... 99.93-2 29.876' 86.0' 88.31 80.6' ;l.Zi 9l.lb 74.Oh 82.6 54 11 71' 3 I eue. 1 I44 6.0 November .... 29.921 29 859' 80.2 82 6e i5.6 '6.71 85.7 73.1 i9.d 90 5 69 3t e2 e. by 11. 339 14.1 rc c December .... 29.977 29.926l 80.1 83.4K 76.0 ii.ig 85.0 c3.2 79.4 sa 12 70 31 1 73 0. 20.3 H.5 lh97. January ..... 29.983 29.9581 79.3 83.3' 74.3 76.4' 85.6 70.6 1 78.1 89 4 I 71 e. eue. 9.9 February.. ... 30.OB 29.990' 7%. 9 83.7' 73.1 78.I.' 86.5 71.0 I 78.8 88 3il ;; e. u.,' s. 5 March ...... 29.990 29.9W 80.1 R3.1' 74.1 75.4f 86.6 71.3 79.0 8s 4t 65 e. e. ' 12.0 Aprll ...... S.985 29.9166 82.6 Si.% i6.9 77.9, 89.0 73.7 81.4 90 I1 5 f.;! e. e. 7.4 Yay ...... 29.947 29.9l7k 83.4 M.3e 78.0 78.5K w.4 76.2 79.8 92 13 11 1s #, e. e.: ~ 9.4 June ...... 29.979 29.971 k 82. 8 85.18 7i.7 79.% 89.9 75.6 &2 2 95 18 $2 6t 75 e. r.r , 11.5 July ...... 29. R89 29.975 88.3 8i.Od F0.6 81.5' 89.9 73.5 81.7 91 lit 27 is e. 10.3 August ...... 90.014 29.994' 84.3 86.4' 82.1 83.3' 89.8 i7.4 R3.6 93 31 178- 2q so e. 10.8 September ... 30.007 29. !489 80.2 84.66 80.1 81.5' 92.1 76.0 &.I 94 13 e2 28 :ti ese. ti. 9 October ..... 29.999 99. 9.241 86.8 88.9 79.7 80.8' 89.6 75.7 H'2.6 91 15t 7.3 3 ' 75 e. 6. E November...... 82.2 ...... i5.6' ..... 87.3' 75.P 81.0 59 l7t 7'2 ...... e.' ...... I...... December ...... 81.8' ...... 74.4' ...... 85.9' 74.73 80.3 e8 2 71 ...... ::::.... ene...... 10.3 1898. 1 30.016 29.991 80.5 82.4 72.5 73.4 51.7 $3.3 77.5 98 4t 70 BH. ene. ue. IO.i January.. .. L.4 .. February ..... 29.989 29.976 73.5 80.3 70.5 70.7 86.1 73.1 79.6 810 12 70 March ...... 29.957 L2.933 78.6 843.5 70.3 70.0 85.6 69.2 77.4 9) I3 65 April ...... 30.018 30.000 87.4 84.3 $2.7 7'2.3 87.9 71.0 79.4 9.. 29 63 May ...... 29.983 29.971 6% 7 85.4 73.2 L3.3 86.7 73.7 80.2 94 17 71 June ...... 30.016 30.008 84.0 86.1. 76.1' 76.6a 90.46 75.0:. 82.7 94 9 iI' July ...... 30.001 29.989 83.7 84.9 76.8 7i.3 89.0 74.z , 81.6 Q3 August ...... 29.M; 29.978 89.7 R5.1 i7.2 78.0 lR8.6 74.8 ' 81.7 September ... 29.999 29.925 81.2 84.4 78.2 7s.3 R8.2 74.0 ' 81.1 October ...... 29.954 29.940 SI. 5 85.6 76.6 78.6 $9.5 73.2 80.8 November.. .. 49.929 29.918 80.9 81.4 75.1 75.7 84.1 71.4 77.8 December ...... I ...... 1 ...... ,...... 1899. 8a m 8p.m 8a.m 8 p.m. 8 a.m 8p.m. 8a.m. sp.in. s a.m. 8 p.m~tia.m. , R ID.!U. , January...... 30.028 30.019 74.5 75 9 69.3 63.8 180.3 71.3 i5.8 74 e. e.. 261 10.9 February ..... 30. 093 30.082 76.0 75.0 69.8 68.0 , 80.2 71.2 75.7 6!l ' ne. 0. 27IJ , 11.2 March ...... 30.058 30.030 76.1 74.2 67.8 66.3 80.2 711 75.6 9 1 83 6'2 r,5 tis ~ U.' ue. "3': I 9.3 rl r 1 April ...... 30.021 30. no3 dh.4 76.3 70.8 69.9 ~ 81.4 73.1; 77.6 24 67 67 15'3 7s 1 e. e. 2.32 9.7 A May ...... 30.039 30.017 80. 7 78.3 73.5 $3.8 84.5 75.4 1 80.0 15 70 70 71 77 0. 22s ~ 9.5 e. ~ ,June...... 30.030 30.023 81.6 78.9 $2. 2 :4.(1 R5.2 T!.! , 7?.? 6 72 72 73 2411 10.0 July ...... 30. OOO 29.997 81.4 i9.7 i5.2 57 73 7;j e. 277 ' 11.5 August ...... 29.964 29.954 81.9 Ro. 2 75.8 m.4 7 74 74 1, $676 e. 28s 12.0 Geptember ... 29 973 29.959 82. 2 80.1 76.2 RI.2 2H 74 74 , i6 e. 254 10.6 October ...... 29.918 29.909 82.1 79.1 75.6 HO. 4 !I 73 ne. 171 7.1 November.. .. 29.937 a.9*3 82. 1 19.1 75.6 79.8 19 73 e. 196 n.? December .... 29.963 29.941 7%0 i4.9 70.3 70.H 21 66 ti5 ~~- The data for!he years 1892 to 1897, inclusive, were complleil from records kept by Mr. Aaucock; thnt for the year IRW frum rec(,rds by Mr Placeumn; and, thnt for 1889 from the United States Weather Bnreau records. The small letters to the right and a llttle above certam memz indicate the uumber of on-er\atioua ini-iug from the column of which they are the means. For iu*tance. a shows oue observatlm miasing. I) two, auii bo vu. * Max.+Min. b Iudicate- that the ma\imnm or miuinium temperature occurred 011 other date. alw 2 portion of Mr. Evelyn's record, say the first ten years, srems rlry, wet, niaxiiiium, aiid minimum. The exposure of these to be more reliable than the subsequent portion, owing, per- instruments was decidedly IJetter and the rrsults, therefore, haps, to deterioration of the instrument or to a lack of inter- uf nivre value than the precediiig series. The barometer was est or care in the observer, or both. As a possilile aid in made by J. Hughes, London, aucl \!as placed in a ~IOOUI011 the arriving at the real value of these old readings, the writer is grouiid floor uf hlr. Haiicock's resitlriice, about SO feet ahove making and preparing for publication a series of compara- sea level. It appears to lie an excellent i~istrum~nt,of the tive readings between the barometer used by hlr. Evelyn and fixed cistern type, the tube is scii~iewliatlarger than the tubes the station barometer in this ofice. of the ]\'rather Bureau haromrters, aiid is inclosed in a Mr. Evelyn's temperature readings are the readings of the wooden case, to wh~chis attached ail ivory scale and vernier. thernioweter attached to the barometer, a fact uukiiown at the ()I] the iiistriimeiit the f(11lowiiigdirections for instrunieotal time the first paper was prepared Although the instrnnient error aucl reducing to sea level are eugraved, viz: 29.90 inches, was exposed in an east room, well arranged for the free pas- -0.05 ; 29.50 inches, -0.04 ; 30.00 iilches, -0.02 ; for every sage of the air, the readiiig can not be accepted as represeut- 100 feet of elevation, ndrl 0.1 inch. As hlr. Ha~ico~li'splace iug the true diurnal or annual ranges of atmospheric tem- was 'io feet above sea level it is presumed that lie addetl 0.07 perature, although the annual average must he correct. inch after declucting the corrections ahive indicated. The The next seriee of observations was made by Rlr. E. A. thermometers were exposed in a Steveusc~ii'sscreeii, placed in Hancock, at that time goverrinient analyst for the island, aud the open about four feet almve a grass-covered lann. The covers the period from 1882 to 1697, iiiclusive. Mr. Francis iiiaxitnnm thermometer was niade I)y Negretti c\: Zanil~ra,the Watts, goverumeiit analyst. for the Leeward Islands, has iiiitiimum by Dring ct Fage, and the dry aud wet IJ~Townsoii kindly supplied many of the details with reference to the & Mercer, all of London. The wet thermometpr was provided work of hlr. Hancock as the latter was workiug more or less with water cup and wick. The aneaiomrter was very si~nilar under the direction of Mr. Watts. to that used by the United States Il'eather BU~PRU,and was I Mr. Hancock was equipped with a very complete set of exposed 011 the roof of hlr. Haiicock's house, about 35 feet nieteorological instruments, including a mercurial barometer, above the ground. The name of the maker of the instruinent n barograph, an anemometer, and a full set of thermometers, does not appear, but the dimeiisions are: diameter of cups, 3

Unauthenticated | Downloaded 09/28/21 02:58 AM UTC AUQUST,1900. MONTHLY WEATHER REVIEW. 333 inches; length of arm from center of axis to center of cup. in summer, is generally eastward or southeastward from some 7 iuches. point north of the Lake region. When the southeasterly When Mr. Hancock gave up observing at the end of 1897. course is pursued the high very often merges with the perma- Mr. C. 0. Plageman removed these instruments to his resi- uent high off the south Atlantic coast, and passes beyond the dence, which is about 200 feet above the sea, and exposed field of observation. In some years. however, the lower lay- them very much in the same way as did Mr. Hancock, the ers of the atmosphere become stagnatecl, and the movement greatest difference being in the anenionieter, which he placed of both highs and lows is sluggish aiid uncertain. upon a platforrri 25 feet above the ground, especially erected The initial movement which led to the hot wave cluriiig for it. Being nom 200 feet above sea, 0.2 iuch was added tc August was the slow drift of an area of high pressure south- the barometer readiiiga to reduce them to sea level. ward and southwestward from southern New York, where it The details of the results of hlr. Haiicock’s and RIr. Plage- wa~located on August 4, to the Ohio and Middle hlissiseippi man’s meteorolngical labors are given in Tuble 3, which it it valleys, in which region it culminatrd ahuut the 8th, in pres- advisable to study in connection with Tahle 1. a# the I~asis Miires ranging froin SO.20 to 30.30 inches. Diiriug the preva- for the latter. In obtaining the de~-poiiitaiid the relative lrtice of high pressures over the eastern half of the United humid~ty,Molesworth’s Psychrometric Tahlps were used. A States pressure was relatively low over the Atlantic south of clay’s wiiicl record began with the ninrniug ohsrrvntion, that the fortieth parallel. is if the ohservatioii was taken at I) a. 111. the miles of wiiid The character of the weather during the heated term, as were counted from 9 a. m. to 9 a. in., and if the oliserv a t‘1011 regards the amount of raiti that fell and the vapor contents was taken at IO a. ni. the mind record \vas counted from 1C of the air, varied greatly. In Kehraska, the Dakotas, and a. ni. to 10 a. 111. RIinnesota great quantities of rain fell. In North Dakota It is unnecessary to enter into a description of the data the average for the State was about fire times the normal. taken from the records of the local ofice of the United Statas The winds were fresh to brisk, mostly slwtherly or sontheast- Weather Bureau, as the iiistrunieiits, method of esposnre and rrly. In Cdorado, Kaiisas, aiid quite geoerttlly east of the reducing, etc , are all kno~vn. It ought to be stated, however. hlississippi, there was a deficieiicy in the rainfall, amouriting that the 8 a. ni. and S p. in. means fur January aiid Februnry. in some States to 75 per cent of the normal. The winds as given in Tahle 1, are those of 1900, and all the other were gentle, and mostly from a southerly qiiarter, except in months, from March to December, inclusive, are those of 1809 certain districts to he nieiitioned later. The periods of ex- It was thonght best to use the January and February iiiraii~ tremely high teiiiperatnre were also times of great dryness, for 1900 hecause the observatiuus were made at 6 a. ni. aiicl tj aid the physical discomfort experienced was not so great as p. m. during January and the first fifteen dnys vf February, would have been the case with lower temperature and higher 1899. The 12 iiooii inems are taken from the Richard haro- humidity. On the other hand it should be remeinbered that, graph traces for 1S99, which are supposed to represent thr almost without exception, the days of inoderate temperature actual readings of the hrometer, therefore 0.03 inch has been mere also days of high humidity, and caused as niuch, if not added to get the sen-level readings. more suffering thau those of very high temperature and low humicli ty. The geographic extent of the hot wave is showii by the THE HOT WEATHER OF AUGUST, 1900. text chart, fig. 3, below. It will he noticed that the warm By ALFRED J. HLNR~,Professor of Meteomlog. weather extended from the hckhone of the Rocky Moun- tains eastward to the Atlantic. The temperature on the In normal sumiiier weather, areas of low pressure (cyclones), monritaiii summits was generally above the nornial, but drift eastward over the northerri third of the Uuited States at throughout the great hasin nnd the Plateau regioii it was irregular iiitervals, generally, however, separated by a period below normal 13s amounts ranging froin 2O to 6O daily. of three or four days. As these lows move across the coiiu- try the districts within their southern and eastern cluadrnuts come successively within the influence of warm south and southwest winds in advance of the cyclone and there results a temporary warni wave. The warm wave is, however, quickly terminated. IJY local rains and thunderstorms. after wliicli the temperature again rises arid the same sequence of events ie repeated. In some years the iiortiial eastward movement uf areas of low pressure (cyclones) is checked ; iii such years they forui ns usual 011 the easteru side of the Rocky Rlouo- tains, or move into the United States from the British Pos- sessions, but instead of drifting eastward persist for days ovvr illontana, the Dakotas, Nebraska, Kansas, C’olorado, and \\‘yo- ming. The barrier to t,heir eastern inovement appears to he the area of high pressure nrhich covers the south Atlantic coast States, and also stretches across the Atlantic to th~ Azores aud the shores of southern Europe. IF’ \A. -.I\! I This area of high pressure is merely a portion of the belt P of high pressure which surrounds the globe having its masi- Fig. 2.-Depnrture from nurinnl tern perattire, August, 1900. mum about the parallel of thirty degrees. It should iiot be Within the general area of high temperature may he found conceived that pressure is uniformly high within this belt. ~mnllareas of excessive heating, as in the nPigh tmrhood of A more accurate conception would be to consider the belt of 5t. Paul and St. Lnuis. The monthly mean teniperatur~for high pressure as consisting of a series of detached areas of 4ugust at St. Paul was 77.2O. a higher averaqe thau has ever high prpsssure separated by trough-like valleys of lower pres- iefore been recorded, and the record goes back to lSd0 (using sure, the whole system having a very slow movement east- ,he Army record made at Fort Snelling). At St. Louis the ward. 4ugust meau was higher than any that had hitherto been The course of areas of high pressure in the United States, ibserved ; the record in this case goes back to 1536.

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