ee Tick oe > : a es ies : eee ee ; : ; : ean Caaat > : cr Bon agrs “ = eat reba 255 SS 8 sf Seen ad, Met aye . SAD ore hee be rnes ~ y’ S “ 2 SPA nen ~~ Naar i : ; eas ae Oe GL tip ALP a etree wa ratanhe he a eat Ss a Pu He Sana: TRANSACTIONS BROYAL SOCIETY EDINBURGH. VOL. XIX. PART II. CONTAINING THE q GENERAL RESULTS OF THE MAKERSTOUN MAGNETICAL AND METEOROLOGICAL OBSERVATIONS, WITH DETAILED TABLES OF RESULTS FOR 1845 anp 1846. Bis *, oa a EDINBURGH: _ PUBLISHED BY ROBERT GRANT & SON, 82 PRINCES STREET; AND q WILLIAMS & NORGATE, 14 HENRIETTA STREET, _ COVENT GARDEN, LONDON. MDCCCL. eg y ee — * GENERAL RESULTS OF THE OBSERVATIONS JAGNETISM AND METEOROLOGY, MAKERSTOUN IN SCOTLAND, IN THE OBSERVATORY OF GENERAL SIR THOMAS MAKDOUGALL BRISBANE, BART., G.0.B., G.C.H., D.C.L., LL.D., F.R.S., F.R.A.S., H.M.R.I.A., PRESIDENT OF THE ROYAL SOCIETY OF EDINBURGH, AND CORRESPONDING MEMBER OF THE INSTITUTE OF FRANCE, WITH DETAILED TABLES OF RESULTS For THE YEARS 1845 anp 1846. ORMING VOL. IX. PART II. OF THE TRANSACTIONS OF THE ROYAL SOCIETY OF EDINBURGH. By JOHN ALLAN BROUN, Ksa., DIRECTOR OF THE OBSERVATORY. EDINBURGH: PRINTED BY NEILL AND COMPANY. MDCCCL. TABLE OF CONTENTS. | NO. PAGE GENERAL RESULTS OF THE MaKERSTOUN OBSERVATIONS— System of Observation in different years, --++++-.sscesseeeeseesee tee renesseeenee ees 2 xi | | } Maenetic DecLtinaTIion— Mean Declination and Secular Change, Melslainolelslaicicierees cian iinaisicecisrsioctiacacnencom ee 4 xii | Annual Variations— i Mean Declination, eleloreYaletmrataole' ate’ afueteleVelo1 slat ele lota\ele'e,ola'e oles e[ais\ofelalelstalarelele owe clolefeie/ciwia ciele sinvete/ons 7 xil Difference of Daily Means from the Monthly Means, «+++-++++-++.:-csssseeeeeee 11 xiv i Diurnal Ranges, lolefoteiaLele(e{e\elele\xfel¥ f= o\e[e e ate}eTaiais cla, s/eie{ejals eie/a}e\e\s eloiajal ols Ovelaie’ ols s\folcjove_ate\e/siclnictea clea ats 12 xv | Ranges of the Monthly Mean Diurnal Variation, .-....+--.+...sseeeseseeeeees 13 ari ! F Effect of Disturbance on the Range of the Diurnal Variation, «..-........... 15 xvi Mean Difference of an Observation from the Monthly Mean,.--..............+. 16 xvii | INmmber of Positive Wiferences:, t-cccs.scsccncsooscecclesersousessecccceel vertesece ie Seee Probable Error of an Observation from the Monthly Mean, .--.....-.......+. 20 xviii | | Monthly Variations— . Mean Declination, .------.ssseeseeseesen cee ceeccscee tee ceceeeesenerteceennenesetesens 91 xix | Diurnal Ranges, slelefetsrotsiela}e\ejeYela(eheie's\e\elele(s/efstcle\e(e|alsicle\eisielele eisleielsleie(ele’slele elelele\siewiclels cic ie ice +/ainia'e 99 xix Mean Difference of an Observation from the Monthly Mean,-.-.-.-----....++- 24 xix Diwrnal Variations— Method of combining Results for Different Years, «-:---+--+.:+-:seseeeeeeeeeeee 26 XX Results from all the Observations, for each Month,----++...+--+--eeesseveeeereee 28 xxi Results from all the Observations, for Groups of Months,----. ----.-+- seen 32 Xxii Results from Undisturbed Days, for Groups of Months, ---+-+-.c+.seseeeee. 36 XXili Effect of Disturbance on the Mean for a Month and for the Year, ----....- 38 Xxiv Effect of Disturbance on the Mean for each Hour, --.+----++2+seseeeeeeeeeeee eee 39 XXIV Frequency of the Positive and Negative Excursions from the Hourly Mean POSItION, «+. eres eee ee see ee eee eee ec tect ee cence see eeeses eee seers teeseeeneeeneeeee es 40 XXV Sunis of Disturbances from the Hourly Mean Position,...----..++2+-.seseeere 42 XXVi Mean Excursions of the Magnet from the Monthly Mean Position for each Hour, ee ee ee eee ee eee ee eee ee eee ree ee ee 43 XXVil Probable Error of an Observation from the Monthly Mean, «.....+.+--.s2.+e. 46 = xxviii Variations with reference to the Moon’s Hour-Angle,.-+-+--+++++++++++ se eteeees 47 xxix vi CONTENTS. | NO. PAGE HorizontaL Component oF Macnetic Force— Horizontal Component in Absolute Measure, --+--++-++++sssseeeserstceeeeereeeee 48 xs Secular Change from Observations of Absolute Measure, -+-+-++-++++++0++ +00 49 XXX Mean Values of the Variations of the Horizontal Component ------+++.+-..- 51 XxXxl Comparison of the Secular Change from Observations of Absolute Measure with that from Observations of the Bifilar Magnetometer,.--.-.----+..-- 53 XXXii Effect of Disturbance on the Mean Value, -:+--+seeesceecee eee ceceerecetseceees 54 XXXii Secular change employed in Deducing the Annual Variations,-----------.--- 55 XXxii Annual Variations— Mean Horizontal Component, miele lefriereteratcisieraiaieteleieleielsyovotetelelela erejele vets erelate eiiereicie stereisveteieteteteterate 56 XXX Foot-note on the Annual Period Deduced from the Observations at Toronto and (MUniGh,:0--s:sessastseresacogacccoetedssonadteotots ach sz ouuindomeamiccweeseceeee XXXiL Effect of Disturbance on the Monthly Means, ------.-..-.+ Sete eee e ee eeee enews 57 = xxxiiil Mean Horizontal Component from Undisturbed Days, -----++++++++++++e+e+ 0+ 58 = xxxiil Differences of the Daily Means from the Monthly Means,..--------+.+2.+0... 59 ~ xxxiv Diurnal Ranges, stove (sieleravel aye otslelevate ateloteletercleisreielelerereisiele ciefeleieicieiclee cisisioteisicctelomesiealetieteeciemintion 60 XXXV Ranges of the Monthly Mean Diurnal Variation, from all the Observations and from Selected Days, afetafetolc\olelololers ctalels sle)stelsyeleieleloeioie etaretctolelelels clemiseheicten steele elects 61 XXXV Mean Difference of an Observation from the Monthly Mean,.--........e+++++ 63 XXXV Probable Error of an Observation of the Horizontal Component, -.---------- 64 xxxvi Number of Observations greater than the Monthly Mean,.---++--.+++---...++ 65 = xxxvi Monthly Variations— Mean Horizontal Component, iaveisivicieja's eia\s ato alslelel stalaloraie c iaieiete alcletete ei ainoisinle cine tsleig cicero 66 XXXVI Diurnal Ranges, ----:ssceseresscecceceneesssenceceececscece senses seesesenseetensccees 67 xxxvil Mean Difference of an Observation from the Monthly Mean, ...-.---++.++-- 68 xxxvii Diurnal Variations— Results from all the Observations, for each Month,-----+-+++seseeeeseeee ee eeneee 69 xxxviil Results from all the Observations, for Groups of Months,...--.+++++++++--..+5 70 =a Results from Undisturbed Observations, for Groups of Months, -----+----.- 71 xl Effect of Disturbance on the Hourly Means, ---+-+++++--+e+eeeeee eee eee Sete ecees 72 xl Frequency of Positive and Negative Departures from the Hourly Mean Positions, qossosschonesecescreteccmace ees seceaste ces cn ee ce cee ee eee ee 74 xiii Mean Difference of an Observation from the Hourly Mean Position for CACh Hour, ---00esssccerssseseecseceeececssese ees scercetentcceessecsenceesceccssenees 76 xlii Probable Error of an Observation from the Monthly Mean,.---++---+++.+.++ 78 xliv Variations with reference to the Moon’s Hour-Angle, «-+++.+-++s+ee+sseeeeees 79 xliv VERTICAL CoMPONENT OF MaGnetic ForcE— Vertical Component in Absolute Measure, ----- Cate eeeeeeeee eee eneteeeeeeneee ees 81 xlv Adjustment of Balance Magnetometer in different Years, «++++++++++++seeeee+ 82 xlv Yearly Means of the Variations of the Vertical Component with the Secu- lar Change, sbisitesiveiviesciciesisleseceleticeecmacivicniecciscsieweiecucetscticesitcteesechctineemnt 83 xlvi Effect of Disturbance on the Yearly Mean, «--++.+-++e++eseeersseeeenee eee eeeeeens 85 xlvi CONTENTS. Vil Annual Variations— a Baia Mean Vertical Component, SlerafnlalnisseleLefolejejsia\s\eie/sveicja's siaie.clelcleieis sieie s/s e alcieisisisieieisciecicisticls veces 86 xlvi Mean Change of the Vertical Component from Month to Month,.--.-+++.++ 88 xlvii Effect of Disturbances on the Monthly Means, «.-......s+ssessecesscasceecceecs 89 xlvii Difference of the Daily Means from the Monthly Means, «........:6s...se000+ 90 xlvii MTA AUN ATS CH dor ceeeees cee eTans nee seada deine soso se deculsedses sha be iedccseecseeces gl xl viii Ranges of the Monthly Mean Diurnal Variations from all the Observations, AMG EOMsSClLECKEGAR DAYS ancism-loanccciesciieside els svaise.s os vccjeseseirisoscracesessceess 92 xlix General Law of the Ranges of the Undisturbed Mean Diurnal Variation, 93 xlix Mean Difference of an Observation from the Monthly Mean,..-....++--..+00++ 94 xlix Number of Observations greater than the Monthly Mean,..-.........sssse+0 95 xlix Monthly Variations— Mean Vertical Component, Abd cas CHOCO GRC O COT ORCS ORDERS Tae oer SE nr ad sitter 96 l Diurnal Ranges, ereteteve ear ate re are cine nicl aioe oroinicieisie's's clalleich cleo eisicteieie wie eocdat can emecoccices 97 li Mean Difference of an Observation from the Monthly Mean, -..-..+.--+...... 98 li Diurnal Variations— Results from all the Observations, for each Month.--.--+-+-.+ssseseeeececereaes 99 li Results from all the Observations, for Groups of Months,----+---+++.+2.++eee+ 100 liii Results from Undisturbed Observations, for Groups of Months, --------.-.- 101 lili Effect of Disturbance on the Hourly Means, ......---.sessseseeesceeeseeeee seen 102 liv Frequency of Positive and Negative Departures from the Hourly Mean TEE PAVEh > ono n50q650c0 SHORUBEER CSCEE RES DOR Oy CBRE O nee Se ene oe anne 104. ly Mean Difference of an Observation from the Monthly Mean Position for AGH EVOUPNE eee cesses cschns cami amucee syste thee dhcetaussuabaalchowaeees 105 Ivi Mean Difference from Undisturbed Mean Positions for each Hour, --------- 108 lvi Variations with reference to the Moon’s Hour-Angle, «++++-+++s+s++seseeeeeeee 111 lvii Maenetic Dip— Places of Observation for Different Epochs and General Remarks, -...-.--- 113 lviii Observations in 1849 on Original Dip-Pillar, --+.--+..:sessseseeeecee sees ete eeeee 114 lviii Observations to determine Local Error, ------.-.+--sssscesceeesceeseecenceeeecres 115 Iviil Secular Change, a Peaharerale (orelere olala vein rcleis eisicinie eieteraiclaica\a's cicisiels disieid's ce 'celsleceisisw ceiving owacne esis 116 lvili Result of Observations with Inclinometer in different Azimuths, --.---+--++- HL, lix Observations with the Inclinometer of the Royal Society of Edinburgh, --- 118 lix Variations of Magnetic Dip, deduced from the two Component Magnetometers— Similarity between Results for Magnetic Dip and for Horizontal Com- -—_TOIGENG, ced eoctoopdadios0e Shades on asdond caaobaLedanNadoacuda Cag dasdeabc Seanaaete ce 119 lix Secular Change, 506000000 000 sod 09s codoouaS adouboddaauonadadécoon dod bpanonasadopoccacboos 120 lix Effect of Disturbance on the Yearly Mean, ---+++...++:ssecssccveseeeseeesersesees 121 lix Annual Period, from all the Observations, +++:-:+++sssssseseeeeseeeesseeeeneeeees 120 ee lix Annual Period, from Undisturbed Observations, +:++2+s++ssseceseeseceeerse ees 123 lx Annual Variation of Ranges of Monthly Mean Diurnal Variation, --------- 124 lx Variations of Magnetic Dip with the Moon’s Age,+sr--cesrssescesesserecessenees 125 Ix Vul CONTENTS. Variations of Magnetic Dip with the Moon’s Declination,-.-.-- sen seneceeterees 126 Remarks on the Variations of Ranges of Magnetic Dip,------...-+.-ssseeeee ee - 127 Diurnal Variations— Results from all the Observations for each Momnth,-+:--..s+sseeeeeeeeseececeees 128 Results from all the Observations, for Groups of Months,-----2--. «.-+e+ee0 129 Results from Undisturbed Observations, for Groups of Months,:..........-. 130 Effect of Disturbance on the Hourly Means,.---- Sinie.sloin o, alslstelolelelolersloie ei Chews eioereres * 131 Variations with reference to the Moon’s Hour-Angle-..........+--+-+....se0es 132 Tora, Magnetic Force— Absolute Value, Win oleialave:siayoje Steven ialnayesi ate atateiatetetor a raiece ale elora ors otevole Teale elavaaiceaaa ae he Oe 133 Secular Change, Sib ibieteie eicieasSreielgaiota gates Wialcisle eels elsters biel slalevnte pialsterclo eve dies otic Tatar em ee eee 134 Effect of Disturbance on the Yearly Mean Value,.--...:+-++-sseecsereeeeneeeeees 135 Annual Period,.- FOROS ASAE HES HO CES OO TICCTORIOGH rORGBECKLnas AHOBSTAOR Cote aa boobeencsDssGhenos 136 Effect of Disturbance on the Monthly Means,.-++++.+---+eseseseeecesseceeee tenons 137 Annual Variation of Ranges of Monthly Mean Diurnal Variation,......... 138 Variations with Reference to the Moon’s Age,-:+---+:+:+sse+eesceeeeeseseeeeer eee 139 Variations with reference to the Moon’s Declination,:..---+--.++++-:ese+eeeeeees 140 Remark on the Variations of Ranges of Total Force,-.--.++-+.-++0+-sseseeeeeee 141 Diurnal Variations Results from all the Observations, for each Month,----.+.-+--s:sesescreceee scene 142 Results from all the Observations, for Groups of Months,..-....-..--.-+-+0++ 143 Results from Undisturbed Observations, for Groups of Months,---.......--- 144 Effect of Disturbance on the Hourly Means,...---+--+-++-siereeeecaeeceeeeeeeeeee 145 Variations with reference to the Moon’s Hour-Angle,------::..::0+ cesses eeeeee 146 Comzrnep Motions oF THE Maenetic NEEDLE— Process of Projection and General Remarks -++++++++++++++++.seeetecereeeseeeeeees 147 Annual Motions, afalslolaiefereietelevalsievslelsiaisteinictete stave ele clotsielote’cieselevsielerste'e/eveiveislolele stele vetsloiceteccreieeietemreteets 148 Monthly Motions, LJ Sarceiaie eieie es eleleistarerara Talore eiale wealoratatarcleretcToia ste aieioia'eiercioveis wiaraleieie ee etter cte etree 150 Similarity of the Motions for the Positions of the Sun and Moon in De- Olin ations scorns terete ee ccs caus sett aetla ace rnioet auto atece Ra Cee eee 151 Diurnal Motions, sjelel sloleleietetevaraisinretavete eieteleisielela sverelote vale eieisicicie eiatsiaimcicusrere cieleietsis cineteriteicteletteleeisicrsts -153 Foot-note on the Determination of the Epochs of Maximum and Minimum, Perimeters of the Figures of the Diurnal Motions for each Month,-----.-.-- 156 Perimeters of the Figures for Disturbed and Undisturbed Observations,:-- 157 Mean Angular Motions from Hour to Hour,.-++-+--.-:sseesee serene seers see ee ees 158 Diurnal Variation of Velocity of Diurnal Motion and Relation to that of Disturbance, +so--.sseceesecsscerscseeseueeerscteecereeerscesetensercenteeeeennaserees , 159 Variations in the Velocity of Motion not related to Variations of Tem- perature Of the Airyeses:sssceeseeeseeees ceeeeeeeeeeeeeeeneesereeeeerenerctereeeees 161 Relation of Points of Greatest and Least Velocity to the Astronomical Meridian, BORDOS CO DEOC OO MO TUOEHCD 0.90000 OIOOOS DOOUOOODOD SU DOA ON TOO LUIQURO Do OOOOH AIOIIOSS 162 CONTENTS. General Form and Turning Points of the Diurnal Motions,..-+-.+.-.+.+.+s++ Angular Distances between the Disturbed and Undisturbed Hourly Mean POSItIONS, «-+2eeeceeeeerec reece cneesscre cee eeeecec eect teers eeeeees Ae aisialeleiieismiste sia Motions with reference to the Moon’s Hour-Angle, -..--+..++-sssseeesseeeeee AvrorA BOREALIS— List of Aurore Boreales seen at Makerstoun in the years 1843-9,......-+-.. Additional Notes on Aurora Borealis seen in 1847-9,---.+-.....-. sees seeeee ees Diurnal Variations of Visible Frequency of the Aurora Borealis,...-......-- Annual Variation of Frequency of the Aurora Borealis,...---+++++...+++..+6 Foot-note on Results of Mairan, Kaimtz, and Hansteen,.-.+.+...+00++sseeeee ee Annual Variation from Aurore Observed near Midnight,----.+--+...+.....+++ Variation of Frequency of the Aurora Borealis with the Moon’s Age,..--- Foot-note on the Preferability of Mean Latitudes for the Determination of the Laws of Frequency of the Aurora Borealis,----++.+.:s+++++ssseeeees Note on the Theory of the Aurora Borealis,.-.+-+-++++es.sessssseee essere eeeee ees MetroroLocicaL Resutts— Temperature of the Air— Mean Temperature at Makerstoun, with Probable Error,-----.++..+ssss+++00005 Annual Variation,.:---...sereserececescceceeceerec tea ccscrteresteeeseteecsesaneteereees Probable Error of the Mean Temperature for any Month,.----.+--++-++++++++++ Annual Variation of the Diurnal Range of Temperature, and the Ranges Of theVean WitrnaleViariatlONs,-c-c-e--c-cecanevacerecs sine cinetie ewe te sees see Differences of the Daily Mean Temperature from the Monthly Mean,-...... Diurnal Variation of Temperature,--....-.+-.ssesseeeeeeesee nescence eee eee eeneeeseenes Pressure of Aqueous Vapour— Annual Variation, PRY e Tare ter tee ote TN cTeleia avers ara laisse late os Stciora folate siotel ere alice cialaietelelotensrelntearleerg Save cldobelcae Variations with Reference to the Moon’s Age and Declination -.-.---.-..... Diurnal Variation,:---:-...0eeseeceeere ese eeeesce eee eee tee nee e rete econ see een eeeeneeeres Relatwe Humidity— Annual Variation,---+---+.-sceceeceessssseteecee esse ere cee seer seen sees cesenseeneeeseres Variations with Reference to the Moon’s Age and Declination,--------++++ Diurnal Variation,-..-.0-.+:ceceeeeeseeec ec eeteee cee eee eee eseeneeecenneeneeseeseeereees Atmospheric Pressure— Mean Atmospheric Pressure at Makerstoun, dou gupbbooabognodédc sdbodaupundeobb oda Annual Va-iation, and Probable Error for each Month,----++-+++---+sseseee00 Foot-note on the Differences of Mean Pressure at Greenwich and Maker- Quarters giving greatest Range of Mean Pressure,-+-++++++1+-+seseeeeeeeeereeee Annual Variation of Differences of the Daily Mean from the Monthly Mean Pressures, AGOO DE COSTER CORDED COC SDE OROOUGEC CUD DBO DSCC RCCOOBOR ECHR Trobe EnoCnD NO. 163 165 167 169 170 alyal 172 172 173 175 1X PAGE Ixxili lxxiil lxxv lxxv Ixxix Ixxxi lxxxi Ixxxi 1xxxi lxxxii Ixxxli lxxxili Ixxxiv lxxxiv lxxxv |xxxv Ixxxvi lxxxvi Ixxxvli lxxxvil Ixxxvili )xxxix 1xxxix XC CONTENTS. NO PAGE Annual Variation of the Diurnal Range of Atmospheric Pressure,------.--. . 193 x¢cil Variation of the Diurnal Range with the Moon’s Age,.+-+-++++sseeseeeeeeeeeee 194 xcili Variation of the Diurnal Range with the Moon’s Declination,..-----.....+++. 195 xcili Diurnal Variation of the Atmospheric Pressure,---+-++++e+eeeseeeeeeeeeeeseee ees 196 xciv Amount of Oscillation in the Diurnal Variation, ...++---++6++--sesceeeee sensor cee 197 X¢cV Pressure and Direction of the Wind— Remark on the Observations from which Results are deduced,---+-++++++++--. 198 xev Annual Variation of the Mean Pressure,:-+-:seeeeseeessseecssceeseecceesreesteseee 199 xevi Variation of Pressure with the Moon’s Age,.-----s+sssesssseereeeees se teeeeeeees 200 X¢evi Variation of Pressure with the Moon’s Declination,.---.+++++++se+++sessceeeees 201 x¢evi Diurnal Variation of the Mean Pressure,-----+-seeecseeseeceecseceeececeecenseeres 902 xevii Annual Variation of the Number of Hours at which the Wind blew,--:---- 203 = -xevili Annual Variation of the Mean Pressure while blowing,--.-+++-+++++++-+++e+++- 204 xevili © Diurnal Variation of the Number of Hours at which the Wind blew,--:---- 205 ~=—s- xviii Diurnal Variation of the Mean Pressure while blowing,-++--+-+++++cseesseeeees 206 = xeviii Yearly Mean Value and Direction of the Resultant Wind,...---. ---++-++++-- 207 xcix Annual Variation of the Pressure and Direction of the Resultant Winds, 208 xcix Annual Variation of the Variability of the Wind,.----.+++-++seeseesesreeeseeeee 209 Diurnal Variation of the Resultant Mean Pressure of the Wind,-----------+ 210 Diurnal Variation of the Direction of the Resultant Wind,...-:++-+.-+-+--.+-- 211 Diurnal Variation of the Variability of the Wind,.----.-:2:.++++seeeeessseeeeee 212 ci Times which the Wind blew from each Point of the Compass,--------+++--++- 213 ci Sums of the Pressures for each Point of the Compass,----+++++++++++++s+eseseeee 214 cil Mean Pressure while blowing for each Point of the Compass,------+++++++++- 215 cll Motions of different Currents of Air— Processes adopted in obtaining the Results,..-+-+-+ssseeeseeeseeeeceeeseneeeenenes 216 cil Classification of Clouds and order of Reckoning of Motions,.-.--.--.++++++++ 217 cli Explanation Of Tabular Results, ..--..cee.secessesccerscreceeseeccscsscesceseescseees 918 eli Combined Results for each Current, .+.---ssscccssscceeccceeeeseceececescnssencesees 990 eli Resultant Direction of each Current, --+-++++ Maicisieleisioive sonia ceisantececemnetres seceteee 920 civ Comparison of Mean Upper Current with the Surface Current, ---+---++:-- 221 civ Comparison of Mean Highest Current with Surface Current,-.-+-++++.++++2+ 222 civ General Conclusions, «-++.sseececceeccseercenccseesseeeec een sseeecssccnseetescresesens 993 civ Hatent of Sky Clowded— Mean Extent of Sky Clouded, ---s.seecereeesseccseencescssceaseeveacceccsnccsennee 994 ev Annual Variation,.+.+-..--eescesccecessccceetecccessccceeccccescecsescsssesereceereeeces 995 ev Variation with the Moon’s Age, -:-++:+ssssseseeeeeeeeeeesssenseeese nee seeeeeeerees 996 c¥ Foot-note on Statement by Sir John Herschel,------+0++e++esee0+-+e+ es eeeeseees evi Variation with the Moon’s Declination, ---.++ssessseseeeeeersceeeeereeeeeees sees 228 evil Ditivrial Variation, »- 50m 19) 40m 18) 50™ 182 20m 19> 5m 18h 25m Bb 10m 115 10m 10h QOm gh 50m 30. These epochs are considerably less certain than those for the maximum, especially when they occur be- _ tween 9" 10™ and 17" 10™, as they depend upon only two years’ observations. The principal minimum occurs between 8" and 11" p.m. in the months from September till March, in the latter month the westerly declina- tion at 8 a.m. differs little from that at 11" p.m.: in the remaining months the minimum occurs between 65 20m and 7h 40m a.m. The morning minimum occurs earliest in June and August; the evening minimum occurs earliest in September. 31. Secondary maxima and minima of westerly declination are shewn with moderate distinctness in some months, but the epochs vary so much from one month to the next as to render it doubtful whether they are other- wise than accidental : clearer results may be expected from the combinations of the means for two or three months, if sufficient care be taken that only those months are combined which exhibit separately similar cha- racteristics. A careful examination of the projected means, seems to shew the combinations employed for the following Table, as those best fitted for exhibiting distinctly the changmg character of the diurnal variation. a XX1l GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. TABLE 13.—Diurnal Variations of Westerly Declination for different periods deduced from Table 12. Six Months. March. 5 Twelve April. 5 , g Sept. to March Months. § Feb. to Aug. — 1-97 ~| —1-85 —1-69 | —1-96 Sepa as = 1-08) |) = 9:02 —1-03 | —2.48 —0:96 |-—3-11 —0-49 | —3.48 — 0-45 “| —3-64 —0-27 | —2-97 +0-40 | —1-44 See) | SST +3-61 | +4-00 +4.61- | +6-13 +4-57 | +6-89 +3-68 | +6-02 49.93 | 414.36 +1-05 | +2-67 +0-14 | +0-89 —0:92 | —0-27 —1-49 | —0-71 =)2:60) |= del 4 = 11533} — 1-63 12:69 a lg=alegs KH OOWMDNMIANKWNH OS — 32. The following are the epochs of maximum and minimum westerly declination from Table 13 in apparent time : Dec. Jan. Feb. Mar. April. May. June. July. Aug. Sept. Oct. Noy. Max. 0» 560™ p.m. J) 5™ p.m. 1h 15™ p.m. 0» 50™ px. OF 35m px. Min. 82 p.m.—11" P.M. 8) Om a.m. 65 30™ a.m. 6b 40™ 4M. 85 pw. l1) pan 33. The form of the diurnal curve is the same for each of the periods of three months; the westerly declina- tion decreases regularly from the maximum till about 8" p.m., whereas in the curves for the summer months, the rate of decrease receives a check about 55 or 6" p.m. (see Plate I.) No secondary maximum or minimum is shewn in these means, but the magnet is nearly stationary for several hours in each case, namely from 8" to 11" p.m. in the months from September to February ; from 8" p.m. till 62 s.a. in the mean for Mareh and April, from midnight till 3 a.m. in May and June; and from 9? p.m. till 3° a.w. in June and July. The magnet is stationary for nearly twelve hours about the 23d of March: the transposition of the minimum of westerly declination from before midnight till about 8" a.m. takes place very gradually in March and Apmil; this does not appear to be the case, however, in the return of the minimum from 7" a.m. to before midnight, which occurs about three weeks before the autumnal equinox. 34. When we examine the diurnal curve deduced from the observations for the whole year (Plate I.), we ob- serve a secondary maximum of westerly declination occurring at 2" 40™ «.m., nearly equal minima occurring at 11" p.m. and 6" a.m.; this secondary maximum is evidently due to the occurrence of the minimum for one half of the year about 10" p.m, and for the other half about 7° a..; The mean for the year therefore does not represent, as far as these results are concerned, a real phenomenon ; it is a combination of two distinct results. | 35. The previous conclusions are obtained from the means of all the regular daily observations ; no observa- | tion has been rejected how ever much affected by magnetic irregularity ; we have still to inquire therefore to what extent irregular causes change the diurnal variation. A method has been already proposed and employed | DIURNAL VARIATIONS FOR THE MAGNETIC DECLINATION. xxiii ns ' (Makerstoun Observations for 1844, p. 339) for the determination of this question; namely, by the selection of / those days in each month which appear to have been nearly unaffected by irregular disturbance; a method _ which it is conceived is considerably preferable to that of rejecting only those days affected with large magnetic _ irregularity. The variations for ten days in each month of 1844 will be found p. 339 in the volume for that year, and for seven days in each month of 1845, p. 5 of the present volume; from these two Tables the follow- ing Table has been formed :— TABLE 14.—Diurnal Variations of Westerly Declination for different periods, deduced from Days selected as free from irregular disturbance, in the Years 1844 and 1845. Six Months. March. Mahe} Twelve | 3 April. ; are Months. — 0-99 — 0-99 KH OOONANHKWHWK OS — } 36. The numbers in Table 14 will be found projected in dotted lines, Plate I., where the differences of the | results from the whole series, and from the undisturbed series, will be at once apparent. The following are the epochs, in apparent time, of maximum and minimum westerly declination, deduced from the series of Table 14. | Dec. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. _| Maximum, O04 35™ p.m. 12 5™ pM. Ob 55™ p.m. Oh 50™ p.m. 0» 30™ p.m. Minimum, 5h 40™ a.m. 7» 40™ a.m. 6 45™ a.m. 6> 35™ a.m. 7h 30™ a.m. Beeiipavlaxmum, PORVIHM AGN Y) pusteinssce0S) (). laciddadsmeete | Oh. | ~ er ebdesineses 2h Om aM. Minimum, TOS ENTS, ie lm 5 3 eerie 7 MI a BE OS ae Re 9h 30™ p.m. 37. The principal results from the undisturbed series for the diurnal variation are as follow :— In the quarter, September to November, the minimum of westerly declination is shewn with nearly equal distinctness at night and in the morning; a well-marked secondary maximum occurring at 2" a.m.: a similar result is exhibited in the following quarter; the morning minimum, however, being less distinctly marked than that in the evening. In both cases we find, in opposition to what has been previously conjectured, that the removal of days of disturbance causes the distinct exhibition of a morning maximum previously masked by dis- turbance. The means for each month from September to February shew the secondary maximum; it is seen with least distinctness in January. In the couples of months from March till August, no secondary maximum is shewn, the north end of the magnet moves eastwards from about 1» p.m. till 72 or 8> a.m., but with less velocity between 5" p.m. and 3 a.m., than before the former and after the latter hour. MAG. AND MET. obs. 1845 anp 1846. f XX1V GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 38. Diurnal Variation of the Effect of Disturbance on the Mean Declination—When we deduce the yearly mean declination from the days selected as free from intermittent disturbance (No. 35.) we obtain the following results :— Mean Declination from all the hourly observations in 1844, =/25° 17£06, -1845, = 252. 11732 SORRR OCEAN GoSAaHE from the hourly observations in the selected 120 days of 1844, = 25° 17’:08 Sealed aiuciacs Sea oa soinslst doecuchuees qeatosereae canes sacieeceameansce teats (GU) seddocconacceon | eS Cia AUPAINS SeAeitortAste sojuiscisieates Sosa vigels volsetels sbfuel Sommer leulodsitiasoctentenineaeeeleteeys 84 days of 1845, = 25° 11739 The effect of disturbances, therefore, on the yearly mean position may be considered zero. When we compare the monthly means, as deduced from the 10 days selected in each month of 1844 and the 7 days selected in each month of 1845, with those deduced from all the hourly observations, we find that the average difference (independent of sign) for the monthly means in these two years is about 02 ; a difference which may be referred with more probability to the effects of regular laws, or the fewness of the observations, than to the effect of intermittent disturbance, which is zero on the yearly mean. It is evident, therefore, that, for the purpose of the present discussion, we may assume, with little probable error, that the monthly mean from both series has the same value (as in Tables 13 and 14), and take the differences of the hourly means in the two series as measures of the effect of disturbance; any possible error in this assumption can affect the values of the dif- ferences but slightly ; the epochs of the maximum and minimum would still remain unaltered. In this man- ner the following Table has been formed :— TABLE 15.—Differences of Disturbed and Undisturbed Diurnal Variations of Westerly Declination, as deduced from Tables 13 and 14, exhibiting the effect of Irregular Disturbance on the Hourly Mean Positions. 39. The conclusions from this Table are,— lst, That the greatest effect of disturbance in increasing the westerly declination occurs In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 1h 40m p.y. 9h a.m. to 1" par. 1» 40™ p.m. 8® a.m. 8? aM. ee Ns Ie HE em ? sho 5 DIURNAL VARIATIONS FOR THE MAGNETIC DECLINATION. XXV Throughout the year, therefore, the effect of disturbance in increasing the westerly declination is greatest be- tween 85 a.m. and 2” p.m.; being near the latter hour for the months about mid-summer and mid-winter, and near the former hour for the intermediate months. 2d, That the greatest effect of disturbance in decreasing the westerly declination occurs In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 8hp.w.—12hpm. 65pm—Ill® pm. 1llbepmM—12' p.m. 9227.mM. 10% p.m. 8) p.w.—11" p.m. 3d, That the effect on the hourly mean westerly declination is zero In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 53° a.m.and 54" p.m. 4h a.m. and 55pm. 52 a.m. and63"p.m. 4? a.m. and 53?p.m. 43) a.m. and 534 p.m. Diurnal Variation of frequency of Positive and Negative Excursions from the Hourly Mean Position.—The number of observations which were to the west of the hourly mean for each month in 1844 and 1845 having been obtained, the following Table was formed, containing the numbers per cent. for quarterly groups of months. TABLE 16.—Numbers of Excursions of the Declination Magnet in 100 which were to the West ; 1st, of the Hourly Means, as deduced from all the Hourly Observations in each Month of 1844 and 1845 ; and, 2d, of those deduced from the Selected Days. With reference to Mean of all, With reference to Mean of Selected Days. Feb. May. Aug. Nov. Feb. May. Aug. March. | June. Dee. March. | June. Sept. Year. April. July. Jan. April. July. Oct. | 55-1 39-9 | 47-1 | 36-1 | 32:3 || 38-8 60-8 . . 43-7 49-0 31-0 31-6 38-8 57:6 3: . 46-2 51-0 40:5 42:4 45:0 47-5 : . 53:8 51-0 44-9 42-4 48-0 44:3 . : 46:8 53-6 36-1 38-0 43-5 46-2 55:6 43-0 47-5 48-0 . . 43-7 . . 58-2 | 66-7 | 50-6 | 56-2 57-7 42-4 . . 66-5 65-4 47-5 58-2 59-3 . 41-1 . 6 67-7 59-5 56-3 62-0 61-4 . . 43-7 9 o 71-5 70-6 65-2 61-4 67-1 | 47-5 : : 70-9 64-7 69-6 58-2 65-9 : p 46:8 : . 60-8 62-1 61-4 66-5 62-7 | 45-6 3 | 67-7 | 65-4 | 65-2 | 68-4 || 66-7 | 44-3 . 3°S 63-3 68-0 58-2 65-8 63:8 44-9 : G 64-6 64-7 63-3 64-1 64-1 65-8 66-7 58-2 53-8 61-1 : 62-0 70-6 56:3 57-0 61-4 48-7 . : 59-5 52:3 41-8 53-2 51-7 47-5 . . 58-2 49-0 43-0 53-8 51:0 57-6 48-7 47-1 38-6 50-6 46:3 61-4 38-0 45-1 34-2 38-6 38-9 67-1 9. 54-4 44.4 40:5 34-2 43-4 61-4 . 39-2 44.4 38-6 29-1 37-8 35-5 41-1 40-0 0 1 2 3 4 5 6 7 8 9 0 1 — 40, The following are the epochs of maximum and minimum frequency of the positive or westerly excursions. | From the Means of all the Observations. From the Means of the Undisturbed Days. | Min, Max. Min. Max. Nov. Dec. Jan. 8) a.m. 8 p.m. 11) p.m. 93h am. ‘Feb. March, April. 10% a.m. 63h p.m. 95 P.M. 9> a.m.—4? p.m. _ May, June, July, 63" a.m, 9» p.m. 8» p.m.-—1® a.m. 10" a.m. a Aug. Sept. Oct. 6" a.m. 93> P.M. 105 p.m,—1 a.m. OP Noon. XXV1 GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 41. If we consider the mean position as deduced from all the observations in each month, we find that the number of observations for which the declination was to the west, is least from 6" a.m. to 10" a.m., and greatest from 6" p.m. to 104 p.m,; the reverse of course holding for the deviations to the east : if, however, we consider the hourly mean position deduced from the days selected free from disturbance, we find that the number of westerly observations is greatest from about 9? a.m. till noon, and that it is least from 8" p.m. till 1" a.m.; which result is nearly the reverse of the other. As the maximum effect of disturbance, in increasing the westerly declination (No. 36), occurs about the same time as the maximum frequency of westerly excursions from the undisturbed position (as seen in the second result), the displacement westerly of the mean position, by dis- turbance, reduces the number of westerly excursions from that position to a minimum (as seen in the first result). The same explanation applies to the other epoch. Diurnal Variation of the Sums of Disturbances of the Hourly values of Magnetic Declination in 1844 and 1845.—The following table contains the sums, for 100 observations, of the deviations of the north end of the declination magnet from the monthly mean positions at the corresponding hours, the latter being deduced from the days selected as free from irregular disturbance. TABLE 17.—Hourly sums, for 100 Observations of Westerly Declination in 1844 and 1845, of the Positive and Negative Excursions from the Approximate Normal Positions for each Hour. Positive (W.) Disturbances. Negative (H.) Disturbances. Mak. Mean Nov. Feb. May. Aug. Nov Feb. May. Aug. Time. Dec. March. | June. Sept. Year Dec March. | June. Sept. Year. Jan. April. July. Oct. Jan April. July. Oct. h. m. 4 A 4 f “ U u u % ¥ 12 10 77 138 73 101 97 272 305 259 339 || 294 13 10 87 144 73 107 102 277 300 253 313 || 286 14 10 114 159 88 157 129 198 264 215 270 237 15 10 135 146 135 177 148 178 208 159 225 193 16 10 128 190 138 141 149 147 171 172 190 170 17 10 109 167 157 225 164 123 110 134 135 126 18 10 178 189 176 286 207 69 72 116 $3 85 19 10 209 203 164 294 218 43 59 118 7 74 20 10 236 218 216 344 254 38 69 80 48 a9 ; 21 10 275 258 252 335 281 40 56 77 73 62 ¥ 22 10 249 230 261 260 251 51 09 66 92 67 } 23 10 217 206 243 260 232 66 72 98 67 76 | 0 10 294 241 219 250 251 595 79 88 67 73 1 10 288 250 224 250 253 72 66 99 94 83 2 10 279 257 219 268 256 64 77 81 91 78 3 10 260 243 188 244 234 112 91 109 131 111 4 10 233 213 159 197 201 122 93 108 109 108 5 10 160 149 95 157 141 150 212 113 127 150 6 10 159 108 71 123 116 294 309 125 251 244. 7 10 97 108 56 97 89 274 292 168 240 243 8 10 62 95 40 70 67 382 304 194 364° |} 311 9 10 76 120 42 52 72 503 348 170 399 305 10 10 77 101 48 62 72 345 312 158 393 302 11 10 52 94. 45 87 70 374 311 | 220 3595 315 | 1 42, The results from the Table are as follows :— 1st, The sum of positive or westerly disturbances Nov. Dec. Jan. Feb. March, April. May, June, July. Aug. Sept. Oct. Is amaximum at 0! Noon. 9» a.m. and 2" p.m. 10h a.m. 82" aM. Is aminimum at 11" pm. 8) p.w.—11" p.m. 81” pn. gh pM. 2d, The sum of negative or easterly disturbances Is a maximum at 85—11 p.a. 9 pat. 121h am. gi» p.m. Isa minimum at 8" avn, 7) a.m.—10® avn. 105 a.m. 8h a.m.—0Oh Noon. DIURNAL VARIATIONS FOR THE MAGNETIC DECLINATION. XXV11 TABLE 18.—Mean Difference of the Observations of Magnetic Declination in 1844 and 1845 from the Monthly Means, at the corresponding Hour in each Year, as deduced from all the Regular Observations. Mean Westerly Difference. Mean Easterly Difference. I Mean Difference. Nov. | Feb. | May. | Aug. . : : : yr. | Feb. | May. | Aug. | Dec. | Mar. | June. | Sept. ear, . foie . | Sept. ar. | . | Mar. | June. | Sept. | Jan. | April.| July. | Oct. . | April. J. ot. ; July. | Oct. | . 2-16) 2-03 | 2-16 1-99 1-63 1-80 | Ae 7ale| 2-01 2-04 1-63 2.73 3-84 3-00 2-90 2-67 1-93 1-64 1-59 1-73 2-12 | 2.04 1-62 1:38 1-61 1-37 1-84 1-73 | 1-69 1-74 | 1-43 1-51 1-33 1-38 SNWHPOFWUINWOKGN ee Oe FE OO ONT oO Be eee eee ett et et RAawWAAWwAARKAAaS TOF ORE OFPNHEWONND 1 Te le ee ee i On 1S) WAMNNMwWWANDANE Pe WOWOFK NOUKHRDNON WOW OO OO VNOND AwWoOoACUORATO ST Or oe A KORN N _ _ b DE RP ee eB eee ee eee ee DD. STAINS HHAOhOGUWDWHwHYHOwY BOWTONWDOHDNHENADRWHA YD NAnKwnAwpAwWwwoWNMNHHE dA wmwadh ee (SU) “N — bo Ky ie) eS co or for) bo we we) SONMWOAP OK UK OMNNONRAONWNWWw Bw AOnnWoOrI yA AR WADE WANS e op) j=) eo bo or DDD DO DD Re eR RB DE CC ww ww wan © or bo ww we oor ee b bo bo noe ae wNnwewoibh OUE mR OO ONDA wD © Oo OuUwB © OO Ks — I BROT DOSNT UE hore ie Bi, ask mertoers ete Wat pee cele 5 43. Diurnal Variation of the Mean Excursions of the Declination Magnet, from the Monthly Mean Positions _ for cach Hour, from the Observations for 1844 and 1845.—In the previous investigations, we have considered the effect of irregular disturbance on the hourly mean position, the frequency of positive and negative exeur- sions, and the sums of the latter referred to the hourly means of selected days ; we have still to consider the mean values of the excursions which may evidently follow different laws from the sums, as the latter may de- pend upon both the number and mean value. Table 18 has been formed in the following manner: Half the sums of the differences of the hourly observations from the monthly means for the corresponding hours being positive and half negative, half the sums were divided by the number of positive excursions to obtain the first portion of Table 18, and by the number of negative excursions to obtain the second portion; the third portion is obtained by dividing the whole sums by the whole number of observations. Table 19 has been formed simi- larly, excepting that the sums of the positive and negative disturbances are unequal (See Makerstoun Observa- tions for 1844, p. 350). The quantities in Table 18 have been termed mean differences, those in Table 19, mean disturbances ; the former being related to the means for all the observations, the latter to the means of the undisturbed days. The epochs of maximum and minimum are nearly the same for both Tables ; those from Table 19 only are given, as it is the best exponent of the laws with reference to approximate normal mean positions. Mean Westerly Disturbance. Mean Easterly Disturbance. Mean Disturbance. Max. Min. Max. Min. Max. Min. Nov., Dec., Jan., 1 p.m. 10 p.m. 6h_9> p.m. 8h a.m. 6-11" p.m. 52 a.m. Feb., Mar., April, 25 p.m. 6511) p.m. 9hpm. 75-10" am. 9 p.m.—1® a.m. 6" A.M. | May, June, July, 85-115 a.m. 9 p.m. 1232 am, 828 am. & 55 Pm. 1235 a.m. & 115 a.m. 5510" p.m. | Aug., Sept., Oct., 83> a.m. 9? p.m. 10° p.m. 8" a.m. 10° p.m. 5? p.m, 44. The epochs given above can be considered only roughly approximative, since the value of the average excursion for the hours about the times noted often varies very slowly. The points of most consequence in | these results are as follow :— MAG. AND MET. ops. 1845 anv 1846. g XXVill GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. lst, The average westerly excursion from the mean position for the hour is greatest in the winter and spring quarters about 1" or 25 p.m.; and about 8" a.m. in the summer and autumn quarters, although the values vary little in the summer quarter from 4" a.m. to 1" p.m., and in the autumn quarter a secondary maximum occurs at 3" p.m. 2d, The average easterly excursion is least about 8 a.m. in each quarter, with the exception of summer, — in which it is equally small at 5° p.m.: the average easterly excursion from the hourly mean of all the obser-_ vations (‘Table 18) has the minimum decidedly marked at 62 p.m, 3d, The minimum westerly excursion occurs about 91 p.m. in all the quarters. 4th, The maximum easterly excursion occurs earliest in winter, about 6° p.m., and latest in summer, namely after midnight; while in the equinoctial quarters it occurs betwixt these epochs, the values varying little from 6 p.m. till midnight. pale The mean excursion, without reference to direction, has its greatest value earliest in winter, about 6" p.m.; about 9 and 10" p.m, in the equinoctial quarters ; and in summer there are two maxima of nearly equal value, immediately after midnight and at 115 a.m., with a secondary minimum apong 62 a.m. j 6th, The mean excursion has its least value about 5h to 6" aM. in winter and spring; a secondary mini- — mum, as noted above, occurs about the same hour in summer, and 4? in autumn; but the actual minimum occurs, distinctly marked, between 65 and 10" p.m. in summer, and, less distinctly marked, about 5° p.m. in autumn. 45. It appears from these results, that the diurnal law of mean disturbance is not constant throughout the year, as has been supposed ; in fact the law for summer is nearly the reverse of that for winter, while that for autumn is nearly intermediate between the two, a secondary maximum occurring in the latter at 98 a.m. In the winter and spring quarters there is a tendency to a secondary minimum about 4 or 5® p.m. TABLE 19.—Mean Disturbances of Magnetic Declination, or Differences from the Monthly Means, at the corresponding Hours in 1844 and 1845, as deduced from the selected series in each Year. Mean Westerly Disturbance. Mean Easterly Disturbance. Mean Disturbances. | Mak. i } Mean || Nov. | Feb. | May. | Aug. | Nov. | Feb. | May. | Aug. | Noy. | Feb. | May. | Aug. | Time. || Dec. | Mar. | June,| Sept. || Year. | Dec. | Mar. | June.| Sept. || Year. | Dec. | Mar. | June. Sept. || Year, f Jan. | April.| July. | Oct. } Jan. | April.| July. | Oct. } Jan. | April.| July. | Oct. | m. / / / ‘ | ‘ } , , / / ’ i ‘ ca ¢ , | « 10 || 0-96| 1-47] 1-02] 1-56] 1-25 | 2-26| 2-88| 2-02] 2-50|| 2-40 | 1-74] 2-22] 1-66] 2-21]! 1-95 10|| 1-00] 1-47] 1-17] 1-68]| 1-32 ] 2-45| 2.94] 1.98] 2.29] 2.33 1-82] 2-22) 1-63] 2-10 || 1-94 10]| 1-23| 1-56] 1-09) 1-85 || 1-44 | 1-84| 2.69) 1-81} 2-34] 2-15 }| 1-56] 2-12] 1-52] 2-14 i 1-83 10|| 1-25] 1-43} 1-50) 2-09|| 1-54 | 1-92] 2-12] 1.44/ 1-96] 1-85 | 1-56) 1-77) 1-47] 2-01 | 1-70 10|| 1-37] 1-77} 1-92| 1-86] 1-71 } 1-38) 1-84] 1-34] 1-53} 1-51 ] 1-38] 1-81} 1-55) 1-66) 1-60 10|| 1-18] 1-56] 1-82) 2-37]| 1-71 | 1-14] 1-24] 1-18] 1-29]| 1-21 } 1-16] 1-39] 1-46 1-80) 1.45 10|| 1-53] 1-39] 1-74] 2-57|| 1-79 }| 0-82} 1-08) 1-18] 0-93 |] 1-01 } 1-24] 1-29) 1-46} 1-85 | 1-46 10|| 1-57] 1-55| 1-72] 2-52]| 1-83 | 0-64] 0-80| 1-12] 0-93 |] 0-90 } 1-26] 1-29) 1-41] 1-86) 1-46 10]| 1-74] 1-83) 1-92] 2-77|| 2-07 | 0-59] 0-86] 0-92] 0-63] 0-76 | 1-37] 1-43] 1-48] 1-96) 1-56 10 || 1-92} 1-83] 1-94) 2-73) 2-09 | 0-69} 0-95} 1-11] 0-95|} 0-93 } 1-58| 1:57) 1-65} 2-04 i 1:71 10] 1-76] 1-78} 1-88| 2-23 | 1-90 } 0-87]-0-84| 1-08} 1-11 || 0-99 } 1-50} 1-45} 1-64} 1-76 1-59 10]| 1-78] 1-66} 1-98| 1-96 || 1-85 } 0-84] 0-95] 1-26] 1-00] 1-02 | 1-42] 1-39] 1-71] 1-64)| 1-54 0 10}| 2-17] 1-84] 1-68] 1-83|] 1-89 } 0-86) 1-14] 1-27] 1-06} 1-08 { 1-75] 1-60} 1-54] 1-59) 1-62 10 || 2-27] 1:84] 1-92] 1:90] 1-98 0-98} 1-03) 1-18 | 1-38 |] 1-14 | 1-80] 1-58 | 1-62} 1-72) 1-68 10 || 2-16] 1-98] 1-73] 2-10] 1-99 } 0-90] 1-08} 1-11} 1-26 || 1-09 | 1-72 1-67) 1-50} 1-80) 1-67. 3 10] 1-98} 1-82; 1-61] 2-27] 1-91 | 1-63] 1-36] 1-31| 1-42]} 1-42 | 1-86} 1-67) 1-49] 1-88] 1-72 | 10} 1-88} 1-51] 1-41] 1-74] 1-63 | 1-60} 1-58] 1-23] 1-27] 1-39 }| 1-78} 1-53] 1-34] 1-53) bod 10|| 1-34] 1-43] 1-14] 1-48]] 1-36 } 1-85] 2-23] 0-97] 1-36] 1-55 } 1-55] 1-81) 1-04] 1-42) 1-45 > 10] 1-37] 1-10) 0-82] 1-14 | 1-13 | 3-52] 3-03] 1-09) 2-72]| 2-49 | 2:27 | 2-09| 0-98| 1-87 || 1-80 10]) 0-99} 1-15] 0-72] 0-95 || 0-96 | 2-67| 2.75| 1-37| 2-43] 2-26 } 1-85] 2-00) 1-12] 1-69) 1-66 10 |) 0-82] 1-05] 0-58] 0-91 || 0-86 | 3-08| 2-77] 1-48| 2-96] 2.54 | 2-22] 2-00| 1-17] 2 17 || 1-89 10] 0-70] 1-35} 0-51] 0-77 |) 0-83 | 3-33] 3-13] 1-43| 3-03] 2-69 | 1-90] 2-34] 1-06] 2-26 | 1:89 10 | 0-99] 1-14] 0-62] 1-07} 0-95 | 2-84} 2-80 | 1:29 | 2:77 || 2-43 } 2-11 2-06 | 1-03 | 2-28 l 1-87 10|| 0-71 | 1-00} 0-64] 1-05 | 0-86 {°2-95| 2-94] 1-70 3-02) 2-63 } 2-13] 2-03) 1-33] 2-21 | 1-92 | | } \ | u 46, Diurnal Variation of the probable error of an Observation of Magnetic Declination —It appears from | the previous ees that the best hour to make an observation of magnetic declination in winter and fs spring, is about 6" a.m.; in the summer quarter, from 5" p.w. to 10" p.m. ; and in autumn from 44 to 5" pa. | DIuRNAL VARIATIONS FOR THE MAGNETIC DECLINATION. XX1X The least and greatest values of the probable error of an observation from the monthly mean of the hour, for Makerstoun in 1844 and 1845, were approximately as follow :— Winter, Least Probable Error, 54 a.m. = 0°8 Greatest Probable Error, 6" p.m. = 1/:8 RE Oo 8 Heal wi 8 i sia v0 TRON Mig BONED a OM tis tanta vance wdyd er ecialo olen OE pent, helo 1, S;DINEAGTE, cos Mane Seat CoE e Eee GIP ENECe—— 0 Oem ys ie Merce eyed olay tis EVA onl! Ave 1% RHPA oe Se. Sasoicoinss's.oeaioe hee UP EMP eC OMe Bs Wika Foie te cu ves etaacls 9 Pim.) = 17-6 It is obvious, however, that even at the same place the probable error will vary with the year. In 1847, the probable error of an observation would have been greatly increased by the excessive magnetic storms of that year: neglecting these rare and excessive disturbances however, the values given above cannot be far from the truth. Variation of Magnetic Declination with reference to the Moon's Hour-Angle-—The following Table has been constructed from Table XI. 1844, p. 342, and Table IX., p. 6, of the present volume. b * TABLE 20.—Variations of Magnetic Declination with reference to the Moon’s Hour-Angle for the | Winter and Summer Lunations, and for all the Lunations of the Years 1844 and 1845. Winter Lunations. i Summer Lunations, 1845. Mean. | 1845. Mean. —0-11 || —0-23 | +0-03 | +0-36 —0-04 | +0-13 +0-16 +0:27 +0-33 +0-36 | +0-19 ‘ 02 || —0-03 — 0-40 — 0-42 — 0-32 47. It appears from this Table, that the mean declination varies with the moon’s hour-angle, as follows :— Ist, In winter (when the moon is in opposition north of the equator) the maximum of westerly declina- tion, for this variation, occurs when the moon is on the meridian of 11%, or about an hour before the inferior transit ; the minimum occurs between 4" and 5” before the superior transit. The group for each year gives almost exactly the same result, but the range of the variation in 1844 was 1/2, while in 1845 it was under 0’-6. | 2d, In summer the declination needle has a double easterly and westerly motion. The maximum westerly declination occurs about 25 hours after the superior transit. The minimum westerly declination occurs about 6 hours before the superior transit. A maximum westerly declination occurs at the inferior transit. A minimum westerly declination occurs about 8 hours after the superior transit. _ The results for the summer lunations in the two years agree to a considerable extent ; the maximum at the inferior transit, however, is not nearly so distinctly marked in 1845 as in 1844, The range of the varia- tions for the summer lunations in the two years, is for 1844 = 0-9, for 1845 = 0/8 nearly. | 8d, The result from the lunations during the whole year, is a combination of the two results previously given. The principal maximum occurs at the inferior transit, and the principal minimum about 6 hours after it. | __ Several single lunations confirm the accuracy of these conclusions. See the volume for 1844, pp. 342, 343. Xxx GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. HorRIZONTAL COMPONENT OF MAGNETIC FORCE. 48. The observations in connection with this element are of two classes :—1st, Observations for the abso- lute value of the component, made by the method of Gauss ; and, 2d, Observations of the bifilar magnetometer for the variations of the component. The observations for the absolute value were made with two different instru- ments ; first, from 1843 till April 1846, with a 15-inch deflecting bar, by Gauss’s original method; and second, after April 1846, with 3-65-inch deflecting cylinders, by Dr Lamont’s modification of Gauss’s method: the whole processes have been already described in the Introductions to the different volumes of Makerstoun Observations. The following Table contains the computed values of (X) the horizontal component corre- sponding to the reading of the bifilar magnetometer at the time of vibration, and also the values reduced to the mean reading of the bifilar for the year of the observations ; to these are affixed approximate weights, depending upon the number and agreement of the partial results, and employed in obtaining the mean in the last column :-— TABLE 21.—Results of Observations for the Absolute Value of the Horizontal Component of Magnetic — Force, made in the Years 1643—1849, with the Resulting Mean Value, corresponding to the Mean Reading of the Bifilar Magnetometer for the respective Years in which the Observations were made. During Observation. X Reduced to Mean Value of } the Mean = X for the Mean : Weight. : Mean Bifilar Bifilar for the org Bifilar Reading Year. of each Year. [ 1 Values of X. Reading. 511.5 33-3512 511-1 3:3807 November 8 510-9 3:3732 November 14 507-6 3-3757 December 18 615-2 33813 . 1844. February 524-6 3-3851 March 520-8 3-3793 May 535-7 3:3816 August 540-7 3-3852 December 26 539-5 3-3789 December 30 534-9 3:37.27 1845. December 29 548-9 3-3870 December 30 539-1 3-3807 1846. February 16 5532 33910 April 14 562-3 33843 G4 fQ on a S 5) ® =I ® a a ) A a3 ‘ Yet 4 1847. May 31 574-8 3-3842 June 15 576-7 3:3843 September 11 545-0 3-3852 1849. June 19 598-0 3:3873 October 11 568-0 3:3961 3°65-inch Deflect- ing Bar. | | i f | 49. The results for the large bar indicate an increase of absolute horizontal force from year to year between 1843 and 1846 ; those for the small bar exhibit a similar fact, although the considerable difference between the! results for June 19 and October 11, 1849, throw some doubt on the amount of increase. From these observations the increase of the horizontal component in absolute measure (see No. 53.) From 1843 to 1845, = 0:0080 = 0:00400 yearly. From 1844 to 1846, = 0:0082 = 0:00410 .. ... Mean of all, = 0-00388 yearly. From 1847 to 1849, = 0:0071 = 0-00355 ...... HoRIZONTAL COMPONENT OF MAGNETIC FORCE. XXxl 50. The following Tables have been deduced from the observations of the bifilar magnetometer in the same manner as the Tables already given for the magnetic declination. The variations are expressed in terms of the whole horizontal component, the latter being equal to unity. 4 | TABLE 22.—Monthly Means of the Variations of the Horizontal Component of Magnetic Force at Makerstoun. 1843. January | -005055 | -008747) -012663| -014943 | -016211| -017925) - February | -005230/ -008826 -012845 -015013) -016316| -017573 March [| . 27| 008584! -012661| -014988/ -016354| -017806 April | 005439 008760} -012976| -014890 -016354| -017731 | May | 006492 | -009769 | -013679)| -015340) -016716| -017751 June | -006 010233) -014425| -015645 -016570| -018455 July | 006 -010104| -014584| -015572) -016939| -018146 | August | - 010257) -014376) -015407 -016388| -018016 September 007054 | -010542) -014360| -015078 -016233| .017857 October | - 2) 010774) -014344| -015461 -016480| -016981 November 007692) -011579| -014740| -015851 -017161]| .017584 December | -008239| -012065) -015212| -015895 -017775| -018591 51. Monthly Mean Values of the Variations of the Horizontal Component.—The horizontal force has in- creased in the greater number of cases from month to month ; in March or April, and in August or September, the mean is generally less than in the immediately preceding months. The means for 1848 and 1849 are consi- derably less accurate than those for the preceding years, depending as they do on only two daily observations ; and the means for the end of 1846 and for 1847 are much affected by excessive disturbance. » ? TABLE 23.—Yearly Means of the Variations of the Horizontal Component of Magnetic Force, with the Secular Change. Secular Increase. | | | ! Horizontal Component. Each Mean of Year. 4 Years. ! | | | 0-006550 -010020 -003470 -013905 -003885 -015340 -001435 -016625 -001285 -002519 -017868 -001243 -001962 -018711 -000843 -001202 -020611 -001900 001318 | values of the secular change. The secular change appears to have been very large in the years 1842 to 1844, and considerably smaller and more regular in the years from 1844 to 1847 ; the change from 1847 to 1848 is _ smaller, and that from 1848 to 1849 is greater, than for each of the preceding three years. It is not impro- _ bable that the change from 1842 to 1844 is increased by instrumental causes, such as stretching of the sus- pension wires of the magnet, while the variation of the changes in 1847-9 is evidently connected with the great _ disturbances of the year 1847-8. If we take the mean yearly secular change from 1845 till 1849, as probably unaffected by instrumental error, we find it = 0:001318, the horizontal component being unity ; or, if we take the absolute value of the horizontal component, = 3:388, we find— | 52. Table 32 contains the yearly means of the quantities in Table 22, together with the resulting yearly Pe ee a MAG. AND MET. obs. 1845 anp 1846. h XXX GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 53. The mean yearly secular change of the horizontal force in absolute measure, By the observations of the bifilar magnetometer, + 0:00446 By the observations for the absolute force (Table 21), = + 0:00388 Such a near agreement is, perhaps, more than could have been expected: if the observations with the small deflecting bar were neglected (No. 49), the agreement would be even greater. ; 54. It has been shewn, No. 38, that ohn we deduce the yearly mean declination from the days which were © selected as little affected by iitermittent disturbances, the result is almost precisely the same as that deduced from the whole ordinary observations, and therefore from the days disturbed ; a similar comparison being made for the horizontal component, we find as follows :— The yearly mean of the horizontal component, as deduced from the 120 days selected as nearly free from disturbance, In 1844, is greater than that deduced from all the hourly observations of the year by 0:000189. Tri: PB49) iss eictiin ns doe oe Fah wn Biatels elcid oro TORU Laeeiete oe cele d # eine) e elabelocletlag a alete ae eee eC eene Ree 0-000154. The effect of disturbance in both years was to diminish the mean value of the horizontal component on the — average by 0-000172 of the whole component. It was found for 1844 (see the volume for that year, p. 365) that a more careful selection of 60 days (5 in each month) shewed even a greater effect of disturbance, namely 0-000251 for that year. TABLE 24.—Monthly Variations of the Horizontal Component of Magnetic Force, free from Regular Secular Change. | 2 | 1846 | ig | 149 Month. ; 43. : 45. | 1846. ; ‘ 49. to | | to | 1849. | eo | 1847. Prefix. H I A q 0000 ; q || O° 0-000 0-000 0-000 January +213 2 +016 |+100 (+339 February } 5 : | + 204 5 271 | |— 143 |—034 |+ 125 March L 2 | |— 084 |_ 197 | — 098 April L c |\—024 —189 |—344 May ¢ | ; 5 3 2 +308 +262 ee June | t | 35 |+624 |+530 +590 July +172 |+425 +299 |4298 August | 52 | '—017 |-—056 —185 September fle 7.2 é 421 —350 —492 October 3 | 205 5 o7 |—551 —404 —671 November 3a] p 2 |-—¢ | '—287 -—164 -—178 December : 71 |-: (+113 4153 4133 +336 55. Annual Period of the Horizontal Component.—Table 24 has been formed in the same manner as Table 3 (see p. xii.) The secular changes employed in the reduction for each year, obtained in the same manner as for the magnetic declination in 1847-8 (No. 8), are as follow :— 1842. 1843. 1844. 1845. 1846. 1847. 1848. 1849. Yearly increase, 0°003480 0:003804 0:002820 0:001116 0-001368 0:000768 0-001500 0-001920 56. The mean result for the six years 1842 to 1847, given in the last column of Table 24, is probably to be most depended on for an accurate exhibition of the mean annual law, the means for 1848 and 1849 being deduced from too few observations. The mean for the six years 1842 to 1847 shews, that the horizontal component at Makerstoun was a maximum at the summer solstice, and also at the winter solstice ; that tt was a minimum shortly after the autumnal, and shortly after the vernal equinox.~* This result is shewn with * his law, as deduced from the Makerstoun Observations for 1842, was stated to the Physical Section of the British Association. in June 1845, confirmed by a rediscussion of observations made at Toronto in 1842: it has since been confirmed by the observations made in the successive years at Makerstoun, and, as has been shewn in the Makerstoun Observations for 1844 (foot-note p. 357), by Dr ANNUAL VARIATIONS FOR THE HORIZONTAL COMPONENT. XXX11l considerable distinctness in each of the six years ; the variations from it are not greater than might be expected when we take into account the large effect of disturbances, the irregular value of the secular change in some years, and in others the fewness of the daily observations, and consequent imperfect nature of the corrections. These corrections, as deduced from the observations for 1844 and 1845, vary so much as to account fully for many of the minor differences from the mean law in the years 1842 to 1847, and for even the larger differences im the years 1848 and 1849. Upon the whole the summer maximum appears rather greater than the winter maximum, and the autumnal minimum than the spring minimum ; although as thisis not the case in the mean for the first four years (column 10, Table 24), and as very large disturbances occurred in the end of the years 1846 and 1847, which probably increased the autumn minimum of these years, this difference in the minima is perhaps accidental, and might be removed or considerably diminished in a larger series of observations. 57. When we compare the monthly means, as deduced from the 10 days selected in each month as least affected by irregular disturbances, with those deduced from all the hourly observations in the same months, we find the latter less (—) or greater (+) than the former, by the following quantities :— Year. Prefix. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 1844, 0:000; —109 —346 —399 —315 —029 +4018 —021 —108 —062 —507 —164 —234 1845, 0-000 | —301 —160 —260 —143 —0382 +021 +003 —119 —109 —251 ~—111 ~—377 Mean, 0:000 | —205 —253 —329 —229 —0380 +4019 —009 —113 —085 —379 —137 —305 In each month, with the exception of June, the mean deduced from the undisturbed days is greater than that deduced from all the observation days; and the excess is greatest in March and October, the months of greatest disturbance : the effect of disturbance on the means for the months of May, June, and July, is very small, nearly zero. ‘ 58. As the above effects of disturbance seem to obey a law similar to that of the annual period of the mean, it will be interesting to consider the law for the latter, as deduced from the nearly undisturbed 10 days selected in each month of the years 1844 and 1845. The following are the mean variations, deduced from all the daily observations in 1844 and 1845, as in Table 24. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. Mean of all, 0-000 | +082 4044 —224 —280 +132 +494 +373 +4022 —314 —294 —065 +098 Correcting these by the mean quantities in No. 57, we obtain the variations of the monthly means from the nearly undisturbed days of 1844 and 1845. | ies, } 0-000 | +116 +126 —066 —222 —009 +304 +211 —036 —400 —086 —099 +162 The monthly means, deduced from 10 nearly undisturbed days in each month of the two years, give the same law as has already been deduced from the means of all the observations (as in Table 24): in the undis- turbed means, the maximum at the winter solstice is rendered more marked, and it appears probable that the difference between the values of the two maxima may be wholly a result of disturbance, which appears to diminish the winter means considerably, while it rather tends to increase those at midsummer. When a more careful selection of undisturbed days is made, as in that of jive days in each month of 1844, (see p. 365 of the volume for that year) it is found, that the effect of disturbance in diminishing the winter means, and in increas- ing the summer means, is even more considerable than that found above No. 57. Differences of the Daily Means of the Horizontal Component from the Means for the corresponding Months. — The discussion for 1844, will be found in the volume for that year, page 357, the results for 1845 and 1846, are obtained from Tables XVIII. and LVII. of this volume. Lamont’s observations at Munich (1843-5), although by the combinations which he had employed he had failed in detecting the fact. |! Whe following are the variations of the Munich numbers as corrected for secular change in the note cited, the horizontal component at the place being taken as unity. ; Prefix. | Dec. Jan. Feb. Mar. Apr. May. June. July. Aug. Sept. Oct. Nov. Dee. 0000 | +172 —029 —086 -029 —158 4265 +4238 +4280 41386 —-—421 — 328 —045 4172 The value of this confirmation of the Makerstoun law is increased by the fact, that the Munich instrument has a unifilar suspen- sion, and that the processes of observation, reduction, and correction, are completely different from those employed at Makerstoun. XXXIV GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. TABLE 25.—Means of the Positive and Negative Departures of the Daily Means from the Monthly Means of the Horizontal Component of Magnetic Force, with their Differences. Mean Positive Departures. | Mean Negative Departures. Mean ee ce Month. l | | 1844, | 1845. | 1846. | Mean. || 1844. | 1845. | 1846. | Mean. || "| 1844. | 1845. | 1946. || Mean, Prefix. 0:00 0-00 0:00 =* | 0-00 0:00 0:00 0:00 0-00 | 0: \} 0-00 | 0-00 Jan. 0172 | 0316 | 0159 | 0216 || 0215 | 0538 | 0171 | 0308 || 2 || 0191 | 0398 | Feb. 0317 | 0303 | 0284 | 0301 | 0404 | 0303 | 0171 | 0293 |- | 0356 | 0303 Mar. 0445 | 0214 | 0299 | 0319 |) 0712 | 0250 | 0299 | 0420 | 0548 | 0231 April || 0404 | 0285 | 0314 | 0334 || 0472 | 0641 | 0428 | 0514 | 0436 0394 May || 0355 | 0228 | 0346 | 0310 || 0330 | 0387 | 0403 | 0373 | 0342 | 0287 | June 0193 | 0177 | 0441 | 0270 || 0178 | 0225 | 0514 | 0306 || | 0185 | 0198 July 0217 | 0204 | 0314 | 0245 || 0271 | 0297 | 0393 | 0320 | | 0241 | 0242 Aug. 0353 | 0386 | 0393 | 0377 || 0380 | 0241 | 0288 | 0303 0366 | 0297 | Sept. 0248 | 0315 | 0463 | 0342 || 0316 | 0315 | 0540 | 0390 | 0278 | 0315 | Oct. | 0459 | 0285 | 0345 | 0363 || 0494 | 0307 | 0586 | 0462 | 0476 | 0296 Nov. 0280 | 0330 | 0496°| 0369 || 0382 | 0357 | 0390 | 0376 | 0323 | 0343 | Dec. | 0258 | 0358 | 0311 | 0309 | 0413 | 0608 | 0335 | 0452 | 0318 | 0451 | 59, The following are the conclusions from Table 25. 1st, The daily mean value of the horizontal component is both most in excess and most in defect of its monthly mean value in April, and in the months from August to November; while the smallest departures from the monthly means occur about the solstices. 2d, The average negative departure is greater than the average positive departure, in every month of the year with two exceptions, February and August, and the excess of the former over the latter is greatest in April and December. 3d, As both the positive and negative departures obey nearly the same law, we in consequence find, as in the last column of Table 25, that the greatest departures of the daily means from the monthly means occur immediately after the equinoxes, and the least departures immediately after the solstices. We may generalize this result (as in the case of the magnetic declination, No. 11, 4th) thus :—The differences of the daily means of the horizontal component of magnetic force from the monthly means were a maximum when the horizontal component was least, and a minimum when it was greatest. TABLE 26.—Mean Diurnal Range of the Horizontal Component of Magnetic Force, as deduced from the Ordinary Daily Observations. | | Year. an. Feb. | March,| April. | May. | June. | July. | Aug. | Sept. | Oct. | Novy. Dec. | Mean. | | | Prefix. H 0°00 0:00 0:00 000 0-00 0-00 | 0-00 0-00 | 00 | 000 | 0-00 1843 96 | 1567 | 2333 | 4102 | 4119 | | 4128 | 3268 | 2932 2 1609 1844 2750 | 4980 | 4990 | 4510 | 4600 | 4020 | 3690 | : 2510 1845 95 | 2672 | 3276 | 5695 | 4512 | < 4151 | 4597 | 4441 | 3164 | 3565 1846 || 1: 2051 | 3520 | 5663 | 6711 6750 | 5986 | 3947 | 3597 | 2048 1843 || 1846), 1844| 1845) 4882 | 5415 | 5826 | 5439 | 4627 | 3439 | 2639 | 1828 5342 | 4511 | 3860 | 4220 | 4598 | Mean ll | of all | 5112 | 435: 23 | 5019 - ANNUAL VARIATIONS FOR THE HORIZONTAL COMPONENT OF MAGNETIC FORCE. xxxv 60. Annual Variation of the Diurnal Range of the Horizontal Component of Magnetic Force.—The means for 1844 and 1845 only, in Table 26, are comparable with each other. From the last line of Table 26 we find that the mean daily range was least in the months of December, January, and February, and less in May and June than in April, July, and August. These mean ranges are deduced from the ordinary daily observations. When we seek for the absolute ranges, as obtained from all the extra observations made in the years 1844 and 1845 (Table LX, 1844, p. 400, and Table L. p. 28 of this volume), we obtain the following numbers (prefix 0:00) :— oO Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 1844, 2943 3811 C93 6234 5088" 38025-4538 5319 4538 95184 6556 2965 1845, 5758 3009 4268 6138 4733 4054 4174 5270 5062 3759 2864 3995 Mean, 43855 3410 5230 6186 4910 3928 4856 5294 4800 4446 4710 3480 These numbers follow the same law as those in Table 26, they are, however, considerably larger; the im- erease is most marked in the winter months. From the means of both years we may conclude that the mean value of the diurnal change of the horizontal component of magnetic force at Makerstoun in years of moderate disturbance is about 0:0057 in April and August, and about 0:0038 at the solstices, the whole horizontal com- ponent being unity. TABLE 27.—Ranges of the Mean Diurnal Variation of the Horizontal Component of Magnetic Force. || Year. Jan. Feb. | March.| April. | May. | June. | July. | Aug. | Sept. Oct. Nov. | Dec. || Mean. 0-00 0-00 --| 0-00 0-00 0-00 0:00 0-00 | 0:00 0-00 0:00 0-00 0.00 0-00 1843 || 0928 | 0862 | 1674 | 3209 | 3409 | 3615 | 3867 | 3541 | 2698 | 2203 | 1051 | 0724 || 2128 1844 || 0690 | 0875 | 2195 | 3378 | 3644 | 3179 | 3657 | 3501 | 2948 | 2313 | 1305 | 0760 || 2212 1845 || 1742 | 1008 | 2247 | 3585 | 3623 | 3458 | 3651 | 3374 | 3282 | 1877 | 1537 | 1845 || 2387 1846 || 1027 | 0956 | 2333 | 4099 | 5504 | 4822 | 5550 | 5573 | 4427 | 2395 | 2392 | 1099 || 3152 at of all 1062 | 0840 | 2185 | 3482 | 3969 | 3685 | 4148 | 3997 | 3100 | 2169 | 1431 | 0897 || 2452 — 61. Annual Variation of the Ranges of the Monthly Mean Diurnal Variation—From the last line of Table 27, it appears that the range of the monthly mean diurnal variation is least in December, January, and February, and that it is less in June than in May, July, or August. The following are the diurnal ranges of the monthly mean diurnal variations, as deduced’ from the 20 days selected as free from irregular disturbance in the years 1844 and 1845 :— Prefix. | Jan. Feb. March. _ April. May. June. July. Aug. Sept. Oct. Nov. Dec. magneds4, 0682 1833 3154 3279 3209 3417 3080 2988 2030 1291 0875 62. When we examine the mean diurnal ranges as deduced from all the observations (extra and ordinary) made in 1844 and 1845, we find that the means for March and April, and for August and September, are greater than the means for May, June, and July; when we deduce the mean diurnal range from the regular daily observations, as in Table 26, then we find only the mean for April greater than the means for May, June, and July, the means for July and August being greater than those for May and June. So when we consider the range of the monthly mean variation as in Table 27, we find the mean for June less than the means for May, July and August only ; and, finally, in the ranges last given, deduced from the mean variations of undisturbed days, the differences for the months from April to September almost altogether disappear, the excess for July bemg in all probability accidental. This result is similar to that already found for the magnetic declination, and we may draw from it a similar conclusion, that the excess of the diurnal range in the equinoctial months over that for the midsummer months is due to irregular disturbance. 63. Annual Variation of the Mean Difference of a Single Observation of the Horizontal Component from the q | Monthly Mean at the corresponding Houwr—The mean differences for 1844 and 1845 (from Table XXXIV., 1844, p. 368, and Table XXX., p. 17, of this volume) are as follow (Prefix 0-000) :— _ Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. | Mean. 1844, 350 533 823 770 568 400 469 645 587 689 591 521 579 Bie 697 «515 477) 50-503. 42144777 «S10 473 «= 501 699 | 547 Meee o23 524 650 710 535° 410 458 611 598 581 546 610 | 563 XXXV1 GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. The conclusion deduced from the numbers for 1844, and which has been deduced from those for the magnetic declination, No. 16, is also to be obtained from the numbers for 1845, though with less distinctness, owing to the large effect of disturbance in January and December of the latter year (See No, 16.) In the mean of both years March and April shew the greatest mean difference in the first six months (and for the whole year), and August and December the greatest in the second six months: the least values are those for June and July, and for January and February. 64. From this result, June and July appear the months best fitted for observations of the horizontal com- ponent of magnetic force; the probable error of an observation from the mean for the corresponding hour in these months being under 0:0003 of the whole horizontal force. 65. Annual Variation of the Number of Observations which were greater than the Monthly Means for the corresponding Howr.—The numbers of observations in 100 which were greater than the monthly means for each month of the years 1844 and 1845 are as follow :— Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. Mean. 1844,, 53:1 64:8 . 60:1.) 52:1), 52:5, 40-7 47-1. 49°8 : 54:3, 61:2 00:68, 59-6) ieee 1845, 596 568 56:9 55:0 53:2 48:3 503 53:0 53:0 56:2 56:3 57:3 | 54-7 Mean, 56:3 55°38 585 .63°5 52°38 47:0 489 51:4 536 58:7 55:9 58-4 542 From these numbers it appears, that im the year there are, in 100 observations, upwards of 8 more in excess than in defect of the monthly means for the corresponding hour; that June and July were the only months which shewed more observations less than there were greater than the monthly means; that in March, October, and December, the number of observations in excess of the monthly means was greatest, being 17 in 100 more than those in defect. Upon the whole it appears probable in this, as in the other cases, that the numbers for 1844 exhibit the mean annual law with greatest truth, and that the number of positive observa- tions is least at the summer solstice, and is greatest near the equinoxes. MonTHLY VARIATIONS FOR THE HORIZONTAL COMPONENT. TABLE 28.—Mean Variations of the Horizontal Component of Magnetic Force, free from Regular Secular Change, with reference to the Moon’s Age and Declination. After Moon’s | Moon |, S i) Ne Mean. | farthest || 1843. | 1844. | 1845. | 1846. | Mean. North. d. d. 0:00 27— 1 | +0078 pS /— 0048 6=="8 |—0154 9—12 || — 0034 13—15 +0093 16—19 /— 0064 20—22 '+.0035 23—26 || +0094 | 66. Variations of the Daily Mean Horizontal Component with reference to the Moon’s Age and Declination. Table 28 has been formed from the detailed Tables in former volumes, and from the Tables pp. 11 and 32 of this volume. From the means in Table 28 we conclude :— lst, That the mean horizontal component is greatest about the time of conjunction, and least about oppe- sition, or immediately before and after that epoch. This result is shewn with great distinctness in several single lunations in 1844, (see volume for 1844, p. 358 and Plate XIV). 2d, That the mean horizontal component is a maximum, both when the moon is farthest north, and when it is farthest south, and that it is a minimum when the moon is near the equator. This result is shewn with considerable distinctness in the variations for both 1844 and 1845 and with some irregularity in 1843 and — 1846 ; the less value of conclusions from the observations of the two latter years should always be borne in mind. MONTHLY VARIATIONS FOR THE HORIZONTAL COMPONENT. XXXVIl TABLE 29.—Diurnal Range of the Horizontal Component of Magnetic Force, with reference to the Moon’s Age and Declination. After Moon farthest North. Moon’s Age. d. d. || 27— 1 2— 5 6— 8 4 | 9—12 | 7 | : | 13—15 | 16—19 20—22 23—26 || Variation of the Diurnal Range of the Horizontal Component with reference to the Moon’s Age and De- elination.—Table 29 has been formed from the Tables in former volumes, and the Tables pages 12 and 33 of this volume. 67. The conclusions from Table 29 are :— Sh 1st, That the diurnal range of the horizontal component is greatest about the time of opposition, and | least about the time of conjunction; in the mean of the 4 years the range varies little from the time that the moon is 6 days till it is 20 days old; it also varies little during the remaining half lunation, but the value for the former is considerably greater than for the latter. 2d, In the mean of the 4 years the diurnal range is a maximum about 4 days after the moon has attained its greatest north declination; it is a minimum when the moon is farthest north. The means for 1844 and also for 1845 indicate a minimum, both when the moon was farthest north and when farthest south, with maxima during the intermediate periods ; this result seems to deserve the greatest value, agreeing as it does with the conclusion deducible from a comparison of the laws of mean values and ranges, namely, that the range of the horizontal component is a maximum when its mean value is least, and vice versa. TABLE 30.—Mean Difference of a Single Observation of the Horizontal Component of Magnetic Force from the Monthly Mean, at the corresponding Hour, with reference to the Moon’s Age and i: Declination. After Moon’s Varia- Moon Age. 1844, 1845. Mean. Hanae farthest 1844. 1845. Mean fone: North. d. a. || 0-00 0-00 0:00 0°00 a. a. |) 0-00 0-00 0:00 000 14—16 0668 0498 0583 ||+0018 } 27— 1 0533 0519 0526 ||—0036 cj 17—20 0682 0591 0636 ||+0071 2— 5 0655 0643 0649 ||+0087 . | 21—24 0441 0578 0509 || —0056 6— 8 0588 0577 0582 ||+ 0020 | 25—28 0484 0539 0511 || —0054 9—12 0510 0536 0523 || —0039 29— ] 0539 0571 0555 ||—0010 # 13—15 0519 0484 0501 =| —0061 ; 2— 5 0497 0568 0532 ||—0033 | 16—19 0560 0647 0603 ||+0041 6— 9 0605 0556 0580 | +0015 | 20—22 0570 0472 0521. || -—0041 } LoO==13 0731 0493 0612 ||+0047 | 23—26 0675 0507 0591 || +0029 __ (this Table, which are nearly the same as those from Table 29, are as follow :— | ___ Ist, The departure of the horizontal component from its monthly mean value for the corresponding hour, {IS greatest about the time of opposition, and least about the time of conjunction; the actual epochs are imme- dik 68. Variation of the Mean Difference of a Single Observation from the Monthly Mean for the corresponding Howr with reference to the Moon’s Age and Declination.—The results for two years 1844 and 1845 from Table XXXV., 1844, p. 369, and Table XXIX., p. 16 of this volume, are given in Table 30. The conclusions from XXXVIL GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. diately before and after those stated, a secondary minimum occurring at conjunction, anda secondary maximum at opposition ; but these secondary points are probably accidental. 2d, The departure of the horizontal component from its monthly mean position for the corresponding hour is least when the moon is farthest south and also when farthest north; maxima occurring at the intermediate periods (see No. 16). DIURNAL VARIATIONS FOR THE HORIZONTAL COMPONENT OF MAGNETIC FORCE. Diurnal Variation of the Horizontal Component.—The discussions for 1843 and 1844 will be found in the volumes for these years, the Tables for 1845 and 1846 are given in this volume, pages 13 and 34. Table 31 has been formed from all the ordinary daily observations made in the 4 years, in the manner already de- scribed for the declination (Nos. 26, 27.) TABLE 31.—Diurnal Variations of the Horizontal Component of Magnetic Force for each Month, as deduced from the Regular Daily Observations made during the Four Years 1843 to 1846. March. : : ; Nov. 0:00 0843 0884 0855 1039 1162 | 1227 1330 1125 0740 0183 | 0000 | 0104 | 0566 | 0835 1028 1131 1027 1431 | 1428 | 1139 | 1111 O0S66 0878 | Me 0776 SK OOONAOKBRWNrR & — 69. The following are the approximate epochs of maxima and minima in apparent time, as deduced from the numbers in Table 31; the principal maximum is distinguished by +, the principal mmimum by —, Jan. Heb. March, April. May. June. July. Aug. Sept. Oct. Noy. Dee. h. m. h. m. h. m. hm hm “4h m. hm h. m h. m. h. m. h, m. h, m. Min. 2210 —2215 —2215 —2215 22 0 2150 2140 2125 -—2150 -2210 -—2240 —22 40 Max. +40 4245 4415 +545 515 645 6550 6510 +420 +5 +60 +61 Min. —l14 0 +14 0 14 0 ETO) Boccon, | sotaee adeeoy hy Fouaee 14 0 13 0 ll 0 -12 0 Max. +18 0 18 45 1g8 0 WAST “vadoond » donee". | Guncades |) dotods 17 15 16 0 41830 +18 0 The diurnal variation of the horizontal component, at Makerstoun, consists of one maximum and one minimum in the four months May till August, and of two maxima and two minima in the eight months September till April; in each of the four months November till February, the two maxima have nearly : values, and in each of the last three of these, the two minima are also nearly equal; from Mareh till April, DIURNAL VARIATIONS FOR THE HORIZONTAL COMPONENT. XXX1X and from October to September, the morning maximum becomes smaller in comparison with the afternoon maximum ; and in May and August there are traces of the former which wholly disappear in June and July. The forenoon minimum occurs earliest in August, and before 10" a.m. in the four months from June till Sep- tember ; it occurs latest in November and December, and after 10 a.m. in the seven months October till April: the afternoon maximum occurs earliest for the first six months of the year, in February, and for the last six months, in September; it occurs latest in June and December. In order to destroy the smaller ir- regularities, means for groups of months have been taken; the same groups have been used as those already adopted for the magnetic declination (No. 31). TABLE 32.—Diurnal Variations of the Horizontal Component of Magnetic Force for Different Periods, deduced from Table 31. Six Months. March. Twelve April. 5 ‘ Months. 0:00 +0026 | —0110 — 0234 | 0314 —0412 | ~ 0477 — 0691 — 1058 — 1603 —1916 —1977 ~1511 —0784 —0014 +0562 +0942 +1476 +1751 +1803 +1769 + 1260 +0776 +0532 +0197 KOO ONAUHRWNHNH OS —_— — 70. The following are the approximate epochs of maxima and minima in apparent time from Table 32. (See also Plate IT.) oe Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. Minimum, 108 20™ a.m. 102 10™ a.m. 105 O™ aM. 9h 35™ aM. 10° Om a.m, Maximum, 4h Om p.m. 55 15™ p.m. 65 20™ p.m. 5h 45™ p.m. 5h 50™ p.m, Minimum, RN ON ei 2 ee LAVAS ang Nee nase me Lv UE ons leche. Sores 2h Om a.m. _ Maximum, 6h 10™ a.m. SOUP AND TG Ars ala AERTS Ie MUL IIN bis. Tassnhea eae 5h 30™ am, From these means of groups, the forenoon minimum occurs earliest in July and August, and latest in | December to February; the afternoon maximum occurs earliest in December to February, and latest in May and June; the morning maximum occurs earliest in September to November, and latest in the three months _ thereafter ; the after-midnight minimum appears to oceur generally about 2” a.m, __ The previous conclusions are obtained from the means of all the daily observations ; the following Table -) contains means for the same groups of months, deduced from the 10 days selected in each month of 1844 as | free from intermittent disturbance, and the 10 days similarly selected for each month of 1845. See Table | XXVIIL, p. 362, 1844, and Table XXV., p. 14, of this volume. _ MAG. AND MET. ops. 1845 anp 1846. k xi GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. TABLE 33.—Diurnal Variations of the Horizontal Component of Magnetic Force for Different Periods, deduced from Days selected as free from Irreguiar Disturbances, in the Years 1844 and 1845. Six Months. | Twelve Sept. to March | Months. Feb. to Aug. 0-00 0-00 +0046 | +0271 -—0018 | +0149 —0010 | +0038 +0057 | —0032 +0139 | —0063 0227-4) =O182ah +0178 | —0332 +0036 | —0663 |, =10338-||-==1188 —0679 | —1620 —0907 | —1791 —0764 | —1479 —0478 | —0908 —0056 | —0246 +0136 | +0241 +0209 | +0672 +0291 | +0783 +0360 | +1049 +0409 | +1149 +0346 | +1176 +0285 | +0990 +0217 | +0786 | 40185 | +0651 +0130 | +0501 | 71. The following are the approximate epochs in apparent time deduced from Table 33. (See also the dotted curves, Plate II.) Dec. Jan, Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. Minimum, 10 45™ am. 105 25™ a.m. 9h 55™ a.m. 9» 50™ a.m. 10» 10™ «mM. Maximum, 5h 30™ p.m. 7h Om p.m. 6» 30™ p.m. 6 55™ pm, 6h 35™ pa Minimum, 1> 30™ a.m. SUD OPM Wit uececc cts, a aeeoneeteeeee 15 55™ am, Maximum, 6h 35™ a.m. SENS OXNGA SN tcc. aera nae 55 30™ aw. A comparison of these epochs with those deduced from Table 32 will shew, that the effect of disturbance is to accelerate the epochs of the forencon minimum and afternoon maximum, those of the latter beimg most affected. In the undisturbed diurnal variation the afternoon maximum occurs latest in March and April, and in July and August. 72. Diurnal Variation of the Efect of Disturbance on the Horizontal Component—The following result is obtained upon the assumption, that intermittent disturbance which affects the hourly mean position does not affect the monthly mean of the 24 hours ; or, that the differences found No. 57, between the monthly means of the undisturbed days, and of all the days, is due to continuous and regular laws, which have little effect on the relative hourly positions ; it appears very probable from No. 58, that this assumption is not quite accurate, but that the negative quantities in the following Table are too small, and the positive ones too large; those for the summer months, however, must be near the truth, as disturbance had little or no effect on the mean for that group: the error in the values for the other periods cannot affect the epochs of positive and negative maxima, xh TABLE 34.—Differences of Disturbed and Undisturbed Diurnal Variations of the Horizontal Com- ponent of Magnetic Force, as deduced from Tables 32 and 38, exhibiting the effect of Irregular DIURNAL VARIATIONS FOR THE HORIZONTAL COMPONENT. | 5 ay ,fe Disturbance on the Hourly Mean Positions. | | Six Months. _| Mak. Mean Time. } i | Twelve | | | | | j March. Months, F | z March | April. | | a Aug. | | | | 0:00 \ 0:00 | A 0:00 | Om 0:00 | — 0221 | —0218 | 5 | —0196 | ae Olt) | Pate | 2| —0404 | —0216 | —0075 | g — (0647 | —0232 ‘ —0201 || ) | | —0178 | —0210 | 27 —0032 3 15-0172) | —'0260 ¢ | —0027 | 2 | —0143 | —0164 Pall 0025 | p 3 | +0019 | —0136 | —0015 Dial —0038 | —0178 5 | —0093 | g —0179 | —0240 —0013 | On| —0143 | —0193 244 | —0082 +0011 | —0162 +0006 +0042 | —0050 | 3 -—0015 | +0138 | +0062 | +0140 | +0305 | +0145 | +0177 +0360 | +0330 | +0199 +0334 | +0261 + 0307 | +0507 | +0514 | +0202 +0524 | +0430 -0669 | +0261 +0325 | +0393 | +0112 | +0054 | +0401 —0008 | +0002 | +0155 2] —0106 | —0129 | —0097 Sula Oli7on| — 0235 | --0096 | —0189 —0142 | —0253 | ‘—0167 | RK OCOOCONDUKWNWH OC — ; | | | : | 73. The conclusions from Table 34 are,— | Ist, That the greatest effect of disturbance in increasing the horizontal component occurs | | In Dec, Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 35 20™ p.m. and 6? a.m. 4h 40m p.m. 5) OM p.m. 5® 15™ p.m. 35 40™ p.m. In the months December to February there are two maxima of the positive effect of disturbance, the second ‘Maximum occurring about 6" a.m. ; this is also shewn, though less distinctly, in the quantities for March and April. The greatest positive effect of disturbance occurs latest in July and August, and earliest in the months from September to February ; occurring throughout the year betwixt 3" p.m. and 5% p.m. | 2d, That the greatest effect of disturbance in diminishing the horizontal component occurs | In Dec. Jan. Feb. — March, April. May, June. July, Aug. Sept. Oct. Nov. About 1 a.m. 25 aM. Qh-30™ AGM 5> 40™ a.m. 11 p.m. A secondary negative maximum occurs in December to February, about 9 30™ a.m., and in March and April vbout 8" 30™ a.m. The greatest negative effect of disturbance on the hourly mean position, occurs earliest in he months September to November, namely about 11 p.m., it occurs farther and farther after that hour in he months following, till July and August, when it occurs about 5% 40™ a.m. 3d, From what has been said, No. 72, the hours when the effect of disturbance is zero must be less certain, hey are from Table 34. # In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. > jibout 4" am. 10% am. 82 p.m. 10am. 8" pm. 1122 am. 83% p.m, O2% pm. 83> Pm. 11 aM. 7 pM, xln GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. The hours for the months December to February are very uncertain, owing to the irregularity and smallness of the variations. Throughout the year the effect of disturbance is zero about 11" a.m. and about 8 p.m. Diurnal Variation of frequency of the Positive Departures from the Hourly Mean Positions —The number of observations having been obtained for each month in 1844 and 1845, which shewed a greater value of the horizontal component than the monthly means at the corresponding hours, the means of quarterly groups were formed, and the numbers per cent. are given in the following Table. TABLE 35.—Numbers of Observations of the Horizontal Component of Magnetic Force in 100, which were greater than the Monthly Mean at the corresponding Hour in the Years 1844 and 1845, for each Quarter, and for the Year. Feb. May. March. June. | April. July. 51-9 | 50-6 | 48-7 | 51-3 | 46-2 BSP oOoOooOonNnNoaurwnrco’ — or o> Or or Or PB Or GS Or Or Or Or OO or gm oo DN WOO bh bw Opmnwidiatawawyg 74. The following are the approximate epochs of maximum and minimum frequency of positive departures, as deduced from Table 35. Nov. Dec. Jan. Feb. March, April. May, June, July. aug. Sept. Oct. Year. Maximum, 1) a.m. Qh aM. 45 aM. 112 pn. to 11" an. 2) aor Minimum, 7h om. and 1" p.m. 35 P.M. 82 p.m. 4> pM. 34 pM. The numbers in Table 35 present considerable irregularities; two years’ observations appear too few to remove these. In the winter and spring quarters, there is a secondary maximum of frequency of positive de- partures about 9) a.m., a secondary minimum occurring in the winter quarter about noon, and in the spring quarter about 6" a.m. The variation of the numbers is greatest in the spring and autumn quarters, it is least in summer. Hvery hour in winter, with one exception, had more observations greater than the monthly mean for the hour, than there were less ; m spring and autumn, all the hours had a greater number of positive than of negative departures, excepting those from 1" to 54 p.m. The minimum of positive frequency oceurs about 7" a.m. in winter, but in summer it occurs nearer 7* p.w. The hours of maximum frequency of the positive departures, are obviously those of minimum frequency of negative departures. 75. It may be remarked here, that these departures are from the mean position of all the ordinary observa- tions. which mean position is more or less affected by disturbance ; could the undisturbed mean position be well ascertained it would probably be found, as it has been in the case of the declination, No. 41, that the hour of maximum frequency of the positive departures from the disturbed mean position, is nearly that of their mini- mum frequency from the undisturbed mean position ; this, it will be seen, was the case when the selected days were assumed as the normal means, as in 1844. (See volume for 1844, page 372). 76. Diurnal Variation of the Mean Differences of the Values of the Horizontal Component from the Monthiy Mean Values for the corresponding Hours.—Table 36 has been formed in the manner already indicated, No. 43, for Table 18. The numbers in Table 36 exhibit such considerable irregularities, that it is difficult in some cases to determine real secondary points of maximum and minimum from those which may be merely accidental, and which might have disappeared in the combination of a larger series of observations ; the following how- ever, are the approximate epochs as nearly as they can be determined. DIURNAL VARIATIONS FOR THE HORIZONTAL COMPONENT. xhi TaBLE 36.—Mean Difference of the Observations of the Horizontal Component of Magnetic Force, in 1844 and 1845, from the Monthly Means, at the corresponding Hour in each Year, as deduced from all the Regular Observations. Mean Positive Difference. Mean Negative Difference. Mean Difference. Mak. Mean | Nov. | Feb. | May. | Aug. Feb. Aug. ; Feb. | May. | Aug. Time. || Dec. | Mar. | June, Sept. Mar. Sept. Year. Mar. | June,} Sept. | Jan. | April.| July. | Oct. April. Oct. April.| July. | Oct. h m. 0°00 0-00 0-00 0:00 0:00 0:00 0:00 0:00 0-00 0:00 0°00 h 12 12 | 0496 | 0650 | 0425 | 0538 || 0531 0956 0790 || 0733 0774 | 0421 | 0640 || 0616 | 13 12 | 0431 | 0702 | 0413 | 0512 || 0522 1276 0638 || 0721 0906 | 0417 | 0568 || 0606 | 14 12 | 0568 | 0807 | 0385 | 0505 || 0589 1840 0727 || 0921 1141 | 0385 | 0596 || 0718 15 12 | 0395 | 0567 | 0463 | 0415 || 0461 0868 0539 || 0612 | 0686 | 0468 | 0469 || 0526 16 12 | 0392) 0536 | 0410 | 0436 || 0444 0755 2/0491 |) 0565 0627 | 0463 | 0462 || 0497 | 17 12 | 0405 | 0583 | 0369 | 0487 || 0461 7 | 0875 0812 || 0637 0665 | 0402 | 0609 | 0535 | 18 12 | 0416) 0403 | 0414 | 0534 || 0443 0454 | 0708 || 0500 0427 | 0426 | 0609 | 0470 19 12 | 0404} 0451 | 0472 | 0527 || 0464 7 | 0598 0684 || 0534 0514 | 0458 | 0595 || 0497 | 20 12 | 0425 | 0475 | 0506 | 0606 || 0502 0684 0820 || 0601 0561 | 0491 | 0697 || 0547 | 21 12 | 0482) 0529 | 0429 | 0573 || 0504 0845 0700 || 0641 0651 | 0442 | 0630 | 0564 | 22 12 0484 0503 | 0510 | 0546 |) 0513 0740 0873 || 0680 0599 | 0525 | 0672 || 0585 23 12 | 0495 | 0506 | 0555 | 0554 || 0524 0671 0749 || 0627 | 0577 | 0533 | 0637 || 0571 | 0 12 | 0513 | 0529 | 0544 | 0588 ||. 0547 7 | 0573 0637 || 0580 0550 | 0549 | 0612 || 0563 1 12 | 0459 | 0492 | 0529 | 0608 || 0521 0463 0550 |} 0521 0477 | 0545 | 0578 || 0521 | 2 12 || 0422 | 0528 | 0592 | 0607 || 0530 0450 0684 || 0540 0486 | 0545 | 0643 | 0535 | 3 12 || 0401 | 0692 | 0620 | 0723 || 0591 0443 0591 || 0525 0540 | 0589 | 0651 || 0556 | 4 12 | 0435 0632 | 0592 | 0837 || 0606 | 0528 0606 || 0582 0575 | 0545 | 0703 | 0594 6 12 ||.0488 | 0611 | 0472/0591 || 0536 0599 0484 || 0558 0605 | 0491 | 0532 || 0547 | 6 12 || 0794) 0552 | 0512 | 0456 || 0592 0598 0485 || 0569 0574 | 0512 | 0470 || 0580 | 7 12 || 0600 | 0482 | 0480 | 0539 | 0530 0492 0607 || 0585 0487 | 0451 | 0571 || 0556 | 8 12 || 0568 | 0527 | 0433 | 0540 || 0521 0684 0673 || 0576 0595 | 0368 | 0599 || 0547 | 9 12 || 0607 | 0615 | 0426 | 0533 || 0553 0849 0707 || 0663 0713 | 0388 | 0608 || 0603 | 10 12 || 0541 | 0591 | 0411 | 0465 || 0505 0905 0670 || 0712 | 0715 | 0399 | 0549 || 0591 | 11 12 ||-0559 | 0558 | 0400 | 0514 || 0508 0914 0771 || 0701 0658 | 0420 | 0617 || 0589 | lst, The average positive difference of an observation of the horizontal component has its maximum and minimum values at the following hours in the means of the four quarters, the times of the principle values being distinguished by + and — Nov. Dec. Jan. Feb. March, April. May, June, July. Aug. Sept. Oct. Year. Minimum, — 6° am. —7> aM. — 2? a.m. — 35 a.m —5> aM. Maximum, 113° a.m. 33) P.M. + 3? P.M. +4" p.m. +435 pw. Minimum, SS On pas 7h pM. oo:dao-ncn don sisieveislelelsterels anipbo Maximum, + 635 P.M. 22 ALM. A maximum occurs in each quarter between 3" p.m. and 6" p.m., and the minimum occurs in each quarter between 2" a.m. and 6" a.m.; there are, however, several points of opposition: thus, the principal minimum in summer and autumn occurs at the hour of the principal maximum in spring; and one of the two equally- marked minima of winter occurs at the same hour as the principal maximum in summer and autumn, and as the well-marked secondary maximum in spring. 2d, The average negative difference has the following epochs of maxima and minima. Nov. Dec. Jan. Feb. March, April. May, June, July. Aug. Sept. Oct. Year. Maximum, +113" p.m. +2) a.m. +35 AM. +113" P.M. ten DH av Minimum, — 635 aM. 6) A.M. 72 AM. — 3}. aM. — 62am. Maximum, 105 a.m. 9» a.m. +15 p.m. +105 a.m. 105 avn. Minimum, 2h P.M. — 2h p.m. — 82) p.m. — 51 pM. — 9) pm. __ A principal maximum occurs in each quarter betwixt 11» p.m. and 3" a.m.; a secondary or principal maximum occurs betwixt 99 a.m. and 1h p.m. The least values of the negative mean difference occurs about the same _ hours in summer as the greatest values occur in winter, namely, between 8" p.m. and midnight. MAG. AND MET. OBS. 1845 anp 1846, ; l xliv GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 3d, The mean difference, independent of sign, has the following epochs of maximum and minimum. , Nov. Dee. Jan. Feb. March, April. May, June, July. Aug. Sept. Oct. Maximum, +8 p.m. +25 aM. +2) pm. 11 p.m. Minimum, — 62 a.m. — 6" a.m. to 64 p.m. —9> p.m. 332 A.M. Maximum, 105 a.m. docious dau do.todGen age bec BaGiah6 ade bas 10h a.m. Minimum, 38> pm. BGG DOO OBOICGO GOO OObanNOe Horalatevorsioateste 65 p.m. 77. The opposition in the epochs of maximum and minimum is even more considerable for the mean dif- ference than for its positive and negative elements. We find, as has already been found for the magnetic declination, No. 45, that the diurnal law of disturbance of the horizontal component varies with season, and that the law for summer is nearly the reverse of that for winter. In summer, the minimum disturbance occurs about 8" p.m., which is the hour of the maximum disturbance in winter; in summer, the maximum disturbance occurs about 3? p.m., which is the hour of a minimum in winter, which differs little in value from the principal minimum ; the law for autumn also differs considerably from that for spring, the least values of the disturbance occur in the latter between 6 a.m and 6" p.m., while the greatest values occur in the former between 8" a.m. and 4" p.m. 78. Probable Error of Observations of the Horizontal Component—At Makerstoun, in years of moderate disturbance, the probable error of an observation of the horizontal component from the monthly mean for the hour of observation has its least values as follow :— SPLIng eince ne GP ast! GE Dene ime eae). cies oy 8a ote 00005: cosa epee ee Summers... 97 Shp vi | ses BB Aer teh ts reece) econ ee ed ae 0:00033.8.0 255 eee eee Autumn, 3° and 42? a.m.and6® p.m. .................. OE nee ean: 0:0004255.. cee eee Variation of the Horizontal Component with reference to the Moon’s Hour-Angle.—The following Table has been formed from Table XXXTI., 1844, p. 391, and Table XXVL., p. 15, of the present volume. TABLE 37.—Variations of the Horizontal Component of Magnetic Force with reference to the Moon’s Hour-Angle for the Winter and Summer Lunations, and for all the Lunations of the Years 1844 and 1845. Moon’s Winter Lunations. Summer Lunations. All the Lunations. Hour Angel eae 1844. 1845. Mean. 1844, neds iellpanioan: 1844. 1845. || Mean. Lage ai 0:00 0-00 0:00 0:00 0:00 | 0-00 0-00 0-00 0-00 0 O — 0066 | —0018 | —0042 | +0029 | +0050 | +0039 | —0019 | +0014 | —0002 2 25 —0132 | +0131 0000 | +0021 | +0163 | +0091 | —0056 | +0147 +0045 4 20 —0059 | —0107 | —0083 | +0018 | +0081 +0049 | —0021 | —0019 || —0020 6 15 — 0046 | —0046 | —0046 | —0028 | —0004 || —0016 | —0037 | —0026 —0031 8 10 || +0004 | —0112 || —0054 | —0060 | —0182 || —0121 | —0028 | —0143 || —0085 10 5 —0036 | —0021 —0028 | —0012 | +0029 || +0008 | —0023 | +0003 —0010 12 O || +0122 | +0029 || +0075 | +0086 | +0102 || +0093 | +0104 | +0063 | +0083 13 55 || +0099 | +0074 || +0086 | +0157 | +0092 | +0124 | +0128 | +0083 +0105 15 50 || —O0001 | +0123 || +0061 | +6030 | —0039 || —0005 | +0014 | +0049 | +0031 17 45 || +0093 | +0047 || +0070 | —0053 | —0102 || —0078 | +0014 | —0021 — 0003 19 40 || +0065 | —0025 | +0020 | —0126 | —0130 | —0128 | —0031 | —0073 — 0052 21 35 —0028 | —O0081 — 0054 | —0056 | —0055 || —0056 | —0044 | —0068 | —0056 79. The following are the conclusions from Table 37. There are four independent results in this Table, two for the winter lunations of 1844 and 1845, and two for the summer lunations of the same years; the other columns are derived from these: of the four results three give the same law so nearly, that the result for the two years may be derived from either with but litéle error in epochs ; that result from the last column of the Table is as follows :— A maximum of the horizontal component about 14 hours after the inferior transit. As MINIMUM, (eiseieuis see geiaele bw eae Noe RNC een 3 hours before the superior transit. A cMAXTIMN UI, jy 40™ p.m. 4h 95™ p.m. Minimum, 3h 40m a.m. 12> 10™ a.m. 1h 45™ am. 2h 10™ a.m. 2h 30™ a.m. Maximum, 8» 40™ a.m. 82 Om aM. 8» 35™ a.m, Minimum, 02 07 Noon. 0h 0™ Noon. 11h 45™ aM, The conclusions from the epochs for these groups are quite similar to those already obtained from the epochs for the single months. The afternoon maximum occurs earliest in September to November. TABLE 50.—Diurnal Variations of the Vertical Component of Magnetic Force for Different Periods, deduced from Days selected as free from Irregular Disturbances, in the Years 1844 and 1845. Mak. | Dec. March M ral | Sept. || ae Mond wel | arch. ay. July. | welve pon ae April. June. Aug. | ee || Sept. to March Months, Feb. to Aug. 1 3006 0-00 0:00 0:00 0-00 0:00 0:00 0-00 | 0-00 12 13 | —0018 | —0065 — 0063 —0069 | —0079 — 0048 — 0066 — 0057 13 13 | — 0023 — 0069 — 0056 — 0071 | — 0081 — 0052 — 0065 — 0058 14 13 || —0028 — 0038 — 0038 —0060 | —0070 — 0049 — 0045 — 0047 15 13 || —0035 — 0026 — 0003 — 0031 | — 0067 — 0051 — 0020 — 0035 16 13 || —0040 | —0032 | +0030 | +0011 | —0063 — 0051 +0003 — 0024 Waek3 | — 0045 — 0022 | +0060 +0038 | — 0057 — 0051 +0025 — 0013 18 13 || —0049 | +0003 +0077 | +0068 — 0043 —0046 | +0049 +0001 19 13 | —0050 | +0029 | +0083 +0075 | — 0013 — 0031 +0062 +0016 20 13 | —0035 | +0058 | +0071 +0058 | +0014 | —0010 | +0062 || +0026 21 13 || —0034 | +0052 | +0017 | +0030 | +0021 || —0006 | +0033 | +0013 22E13 — 0025 | +0017 — 0047 —0004 | +0002 | —0011 — 0011 —0011 23 13 || —0014 | —0034 | —0112 —0071 | —0012 | —0013 —0072 | —0043 0 13 — 0003 — 0084 — 0126 — 0099 — 0018 — 0010 —0103 || —0057 i ike} | +0015 — 0058 — 0099 — 0081 | +0014 +0014 — 0079 — 0032 p I3" +0043 — (0008 — 0053 — 0040 | +0068 +0055 — 0034 +0010 Sense | +0065 | +0026 | —0007 | +0018 | +0106 +0085 +0012 +0049 4 13 +0066 | +0070 | +0045 | +0071 | +0119 +0092 |} +0062 +0077 5 13 -| +0049 | +0083 +0072 | +0086 | +0100 +0074 | +0080 +0077 6 13 || +0040 | +0070 | +0078 | +0077 +0072 +0056 | +0075 +0065 7 13 || +0039 | +0051 + 0065 +0049 | +0049 +0044 | +0055 +0049 8 13 +0036 | +0033 | +0051 +0031 +0038 +0037 | +0038 + 0037 9 13 +0038 | +0020 | +0018 — 0005 | + 0004 +0021 +0011 +0016 10 13 || +0019 | —0021 — 0022 —0029 —0026 — 0003 — 0024 — 0014 eS —0014 | —0053 — 0052 — 0063 | — 0072 — 0043 — 0056 — 0049 101. When we consider the diurnal variation as deduced from days selected as nearly free from inter- mittent disturbance (No. 85), and as exhibited in the means, Table 50, and the dotted curves, Plate III., we find that the epochs of maximum are considerably altered as well as the whole form of the diurnal curve. The epochs of maxima and minima in apparent time are as follow :— Dec. Jan. Feb. March, April, May, June, July, Aug. Sept. Oct. Nov. Maximum, 35 40™ p.m. 5> 10™ p.m. 62 Om p.. 5h 10™ p.m. 4h 10™ p.m. Minimum, 62 40m a.m. 12 O™ a.m. 12 20™ a.m. 12 40™ am. - 125 55m a.m. Maximum, 8h 30™ a.m. 7h Om aM. 6 55™ aM, 9» 10™ a.m. Minimum, Oh 20™ p.m. 02 O™ Noon. Oh 20™ p.m. Oh 5™ p.m. Hence, in the undisturbed diurnal variation, the maximum of the vertical component occurs earliest in the months December to February, and latest in the months May and June. The form of the diurnal curve is quite different in the months November to February, from that for the other months : in the four winter months the diurnal curve is single, having but one maximum and minimum, liv GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. the latter occurring about 7" a.m., which is nearly the epoch of a maximum in the other months: in the months from March to September the diurnal curve is double, the maxima having nearly the same value in each month, and the minima also being nearly equal ; the form of the diurnal curve from March to September is nearly constant ; in October the morning maximum becomes less marked, and it wholly disappears in Novem- ber. In June the minima occur almost exactly at apparent midnight and noon, that at the latter time being on the whole best marked; the maxima occur when the sun is near the prime vertical. 102. Diurnal Variation of the Effect of Disturbance on the Mean Vertical Component.—The following Table contains the mean effect of disturbance upon the hourly means in each group of months, the assumption being made that the effects of disturbance upon the means of the groups of months are zero ; it will be seen from Nos. 89 and 85 that the means of the days selected as free from disturbance, are rather greater than the means for all the days ; while this difference may be partially due to regular laws, it is also so small, compared with the actual differences in the followmg Table, that the epochs for the zero of effect would be little altered if it were taken into account. It will be seen also that the epochs for each group vary little, though the effect of disturbance, as found No. 89, differs considerably in the different groups; thus, for the group December to February, the mean for all the selected days is 0°000005 greater than the mean for all the days, while the mean of the selected days in March and April is 0-000061 less than the mean for all. TaspLe 51.—Differences of Disturbed and Undisturbed Diurnal Variations of the Vertical Com- ponent of Magnetic Force, as deduced from Tables 49 and 50, exhibiting the effect of Irregular Disturbance on the Hourly Mean Positions. Six Months. Mak. Moen Sept. April. Mean Oct. : Twelve Nov. Months. | 000 | — 0122 —0141 |} —0144 | —0153 | —0150 | — 0120 —0080 | — 0044 | — 0023 | +0001 +0023 | +0035 | +0082 | +0090 +0098 | +0141 | +0157 | | +0163 | +0163 | +0119 | +0043 | | —0015 | —0058 || —0076 | 103. The following are the conclusions from Table 51. Ist, The greatest effect of disturbance in increasing the vertical component occurs Tn Dec. Jan. Peb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 6h 15™ p.m. 6h Om p.m. 6> 30™ p.m. 6" OP p.m. 5» 30™ p.m. DIURNAL VARIATIONS FOR THE VERTICAL COMPONENT OF MAGNETIC FORCE. lv Throughout the year, therefore, the greatest effect of disturbance in increasing the vertical component occurs near 64 p.m. or about the epoch of the maximum for the mean value, No. 100, 2d, The greatest effect of disturbance in diminishing the vertical component occurs In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 2h 30™ a.m. 15 40™ a.m. 2h 50™ a.m. Qh 45™ a.m. 35 30™ a.m. The greatest effect in diminishing the vertical component occurs throughout the year between 1$" and 3} a.M., or rather after the epoch of the principal minimum for the mean value, No. 100. Irregular disturbance, therefore, has the same effect on the value of the vertical component as the cause producing the regular diurnal variation. 3d, The effect of disturbance on the vertical component is zero In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 1127 4.mM.&93"pm. 10° am. &93%p.m. 9> a.m. & 1034 Pm. 103° a.m. & 939 p.m. 945 a.m. & 9" Pim. The effect of disturbance on the hourly mean appears to be zero about the time the sun is on the magnetic meridian. Diurnal Variation of Frequency of the Positive Departures from the Hourly Mean Positions.—The number of observations which were in excess of the hourly mean for each month in 1844 and 1845 having been ob- tained, the means for groups of months were taken, and the following Table was formed. TABLE 52.—Numbers in 100 Observations of the Vertical Component of Magnetic Force which were greater than the corresponding Hourly Means, deduced from all the Hourly Observations in 1844 and 1845. Mak. 4 Aug. | | Nov. Feb. Mean 5 | ; March. April. 45-5 46-1 | 42-9 36-4 35-1 104, The following are the epochs of maximum and minimum frequency of the positive departures for each quarter. Nov. Dec. Jan. Feb. Mar. April. May, June, July. Aug. Sept. Oct. Maximum, 115 p.m.—2b a.m. 2h_4h a.m, Qh__5h am. 115 p.m.—6> a.m. Minimum, 52 pM. 5} p.m. 5 p.m. 53” P.M. It appears, therefore, that the number of positive departures from the mean of all the observations for the hour is least about 54 p.m., or about the time that the effect of disturbance in increasing the hourly mean is greatest, and that the number is greatest when the effect of disturbance in diminishing the hourly mean is least, No. 103: the effect of disturbance on the hourly mean position is so considerable when compared with the whole diurnal variation, that it is evident that the number of departures from the wndisturbed positions must haye their maximum about 5” p.m. and their minimum about 2—3" a.m. Diurnal Variation of the Mean Differences of the Value of the Vertical Component from its Monthly Mean Value at the corresponding Hour.—Table 53 has been formed from Table LIII., for 1844, p. 387, and Table XLIII., p. 24 of this volume, in the manner already described, No. 43, for Table 18. MAG. AND MET. oss. 1845 anp 1846. 0 lvi GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. TABLE 53.—Mean Difference of the Observations of the Vertical Component of Magnetic Force, in 1844 and 1845, from the Monthly Means at the corresponding Hours in each Year, as deduced from all the Regular Observations. Mean Positive Difference. Mean Negative Difference. Mean Difference. Mak a sl (2 eg | Mean Nov. | Feb. | May. | Aug. Nov. | Feb. | May. | Aug. Nov. | Feb. | May. | Aug. Time. Dec. | Mar. | June. | Sept. || Year. | Dec. | Mar. | June.| Sept. || Year. | Dec. | Mar. | June.| Sept. |) Year. Jan. | April.| July. | Oct. Jan. | April.| July. | Oct. Jan. | April.| July. | Oct. | | h.* om. 0:00 0:00 0:00 0:00 0:00 0:00 000 0:00 0-00 0°00 0-00 0-00 0-00 | 0:00 0-00 12 13. || 0159 | 0229 | 0151 | 0187 || 0183 | 0199 | 0533 | 0208 | 0379 | 0311 |0177 | 0320 | 0175 | 0250 | 13 13. || 0147 | 0222) 0183 | 0187) 0185 | 0191 | 0431 | 0252 | 0379 || 0303 | 0166 | 0293 | 0212 | 0250 || 0230 14 13 || 0138 | 0226 | 0173 | 0197 || 0185 | 0259 | 0567 | 6283 0400 || 0352 | 0171 | 0323 | 0215 | 0264) 0243 15 13. || 0142) 0203 | 0180 | 0206 || 0184 | 0196 | 0497 | 0293 | 0409 | 0334 | 0165 | 0288 | 0223 | 0274 || 0237 16 13. || 0136) 0185 | 0151 | 0214 || 0172 | 0195 | 0487 | 0263 | 0389), 0320 | 0160 | 0268 | 0192 | 0276 || 0224 17 13. || 0139 0173 | 0145 | 0181 || 0161 |0185 | 0403 | 0237 | 0351 || 0281 | 0159 | 0242 | 0180 | 0239) 0205 18 13 || 0135 | 0148 | 0140 | 0153 || 0144 | 0179 | 0274 | 0201 | 0304) 0236 | 0154 | 0192 | 0165 | 0204 | 0179 19 13 || 0134 | 0124/0134 | 0143 || 0134 |0151 | 0171 | 0167 | 0198 || 0170 | 0142) 0144 | 0149 | 0166 | 0150 20 13. || 0133 | 0101/0131 | 0130 || 0124 | 0141 | 0145 | 0154 | 0156 || 0148 | 0137 | 0119 | 0142 0142 | 0135 21 13 |] 0125 | 0097 | 0121 | 0120 | 0116 | 0147 | 0126 | 0160 | 0122), 0138 | 0135 | 0110 | 0138 | 0121 | 0126 22 13 ||0120/ 0101 | 0122/0111] 0113 ]0141/ 0112/0137 0120) 0128 |0130 0106 | 0129 0115) 0120 23 13 || 0120 | 0115 | 0132] 0112|) 0119 | 0120) 0115/0124 0106) 0117 | 0120/0115 | 0128 | 0109) 0118 13 || 0137 | 0157 | 0123 | 0163 | 0145 [0122/0131 | 0121 | O111 || 0121 | 0129 | 0143 | 0122 | 0132) 0132 13. || 0140 | 0146/0115 | 0180) 0143 | 0127 | 0124 | 0125 | 0123 || 0124 [0133 | 0134 | 0120 | 0146) 0133 13 | 0163 | 0174! 0113 | 0183 || 0156 | 0123 | 0132| 0135 | 0133 |) 0130 10140) 0150 | 0123 0154) 0142 13 || 0289 | 0251 | 0131 | 0246 || 0220 | 0155 | 0144 | 0139 | 0157 || 0151 | 0202) 0183 | 0135 | 0192 0178 13 | 0333 | 0260 | 0166 | 0282 | 0254 |0179| 0140 0147 | 0180) 0162 | 0233 | 0182 0156 | 0220) 0198 13. || 0392 | 0368 | 0182 | 0359) 0315 |0189 | 0181 | 0152/0198 | 0181 10255 | 0243 | 0166 0255. 0230 5 0447 | 0341 | 0164 | 0285 | 0292 | 0187 | 0188 | 0151 0157 || 0171 | 0264) 0242/0157 0202) 0216 13. || 0336 | 0227 | 0152 | 0213 || 0225 | 0166) 0142 | 0130 | 0148 || 0147 | 0222) 0175/0140 0175 , 0178 13 | 0209 | 0153 | 0124 | 0131 || 0151 |0131 | 0128 | 0122/0131 | 0129 | 0161 | 0139 | 0123 | 0131 | 0139 13 ||/0172/ 0131) 0108 | 0110]| 0127 [0138 0157 | 0119 0180 || 0146 [0153 | 0143} 0113 0137, 0136 13. | 0150 | 0160 | 0103 | 0114 |) 0132 [0176 0246 0121 0189), 0179 10162) 0194| 0111 0142, 0152 13 || 0150 | 0150) 0115 | 0148 || 0142 [0199 | 0273 | 0137 | 0322 || 0222 10171 | 0194/0125 0203) 0173 | | | iH] i=) bo w oO PCV ONaAurBWNWNrH Oo i w ao 105. The approximate epochs of maxima and minima for the mean positive and negative differences, the principal being indicated by + and —, are as follow :— Mean Positive Difference. Mean Negative Difference. ee ——————— oo ooaoaoSooo'' ~ Min. Max. Min. Max. Min. Max. Min. Max. Nov. Dec. Jan. —1045 a.m. “GLE PIMs | |) ciSteeedike GD Prete these — 0» Noon. 525 p.m. S35 pM. +245 a.m. Feb, Mar. April, — 94> aM. +53» P.M, 9) PIM. lb am. —1035 a.m. 62 P.M. Si> p.m. = +2}> aM. May, June, July, 2h P.M. +5> P.M. —10h P.M. +25 A.M. — 0» Noon. S35 p.m. —9h P.M. +4235 a.m. Aug. Sept. Oct. —10$" a.m. +55 pM. — 93) P.M. 4h AM, —11}" a.m. 5h P.M. 8h pM. +35 AM. 106. The mean positive difference has two maxima and two minima in each quarter excepting winter ; the principal maximum occurs between 5% and 6? p.m.; in summer the two maxima have an equal value; the values of the two minima differ little. 107. The mean negative difference has two maxima and two minima in each quarter; the principal maxi- mum occurs between 2h and 3" a.m. ; in winter the two maxima differ little in value ; m the other quarters the secondary maximum is very small compared with the other; the values of the two minima in each quarter differ little. 108. It appears, therefore, that the principal maximum of the mean positive difference occurs at the same time as the secondary maximum of the mean negative difference, and vice versa. It seems probable that if ditfer- ences were taken with reference to mean wndisturbed positions, the secondary maximum would disappear im each case; thus, if we consider that the effect of disturbance is to imerease the mean vertical component to a large extent about 6" p.m, (No. 103, Ist), it is obvious that both the value and the number of the negative departures from this increased mean will be greater than if the undisturbed mean were taken as the zero, It was accordingly found in the discussion of the observations for 1844, (pp. 388, 389), when the mean position was employed as deduced from the days selected nearly free from intermittent disturbance, that the maximum of DIURNAL VARIATIONS FOR THE VERTICAL COMPONENT OF MAGNETIC Force. Ivii the mean positive disturbance occurred about 6" p.m., the mimimum between 11” p.m. and 8 a.m,.; that the maximum of the mean negative disturbance occurred about 2" a.m. and the minimum about 65 p.m., although the values varied little between noon and 8 p.m. 109. The approximate. epochs of maxima and minima for the mean disturbance, independent of sign, (indi- cating the principal maximum by + and minimum by—), are as follow :— Min. Max. Min. Max Winter—Nov. Dec. Jan. — 11) a. +6) p.m. gh p.m. PD AM: Spring—Feb. March, April, — 10" a.m. 53° p.m. 83) p.m. + 135 aM. Summer—May, June, July, 12 p.m. . 52 pM. —105 pm. +35 a.m. Autumn—dAug. Sept. Oct. _ — 11) a.m. 55 P.M. 83" P.M. + 33" a.m. It has been seen that the positive disturbance has its maximum about 54—6? p.m., and the negative dis- turbance its maximum about 2° a.m., so it appears now that the mean disturbance, independent of sign, has a maximum near both hours. 110. In winter the secondary maximum, about 1" 4.M., is very indistinctly marked ; in summer the second- ary maximum, about 5" p.m., is very small compared with the other; the principal minimum occurs in winter about 11” a.m.; that at 10" p.m. is best marked in summer. In this case also, as in the cases of the magnetic declination, No. 45, and the horizontal component, No. 77, the diurnal variation of the magnetic disturbance in summer is nearly the reverse of that in winter. The diurnal variation of the disturbance is very nearly the same in spring as in autumn. TABLE 54.—Variations of the Vertical Component of Magnetic Force with reference to the Moon’s Hour-Angle for the Winter and Summer Lunations, and for all the Lunations of the Years 1844 and 1845. Winter Lunations. Summer Lunations. All the Lunations. Mean, | | | 1844. | 1845. || Mean. 1844, | 1845. Mean. 1844. | 1845. 0-00 0-00 | 0: 0-00 | 0-00 0-00 0:00 | 0-00 | 0-00 —0054 | +0002 || y +0017 | +0007 | +0012 | —0019 | +0005 | —0007 —0086 | +0013 | é —0009 | +0015 || +0003 | —0047 | +0014 | —0016 —0069 | —0039 || 4 —0014 | +0013 0000 | —0042 | —0015 — 0028 —0071 | —0029 — 0022 +0002 || —0010 | —0046 —0014 | — 0030 —0058 | —0031 || —0031.| -—0019 | —0025 | —0045.| —0025 || —0035 —0007 | +0002 | —0009 | —0001 | —0005 | —0008 | +0001 | —0003 +0059 | +0030 | —0018 | +0010 || —0004 | +0020 | +0021 +0020 | +0107 | +0038 y +0007 | +0020 | +0013 | +0058 | +0030 || +0044 +0094 | +0036 | +0039 +0001 | +0020 | +0067 +0020 | +0043 | +0049 |29021 | +0017 | —0020 | —0001 } +0033 | +0002 || +0017 | +0043 | —0014 +0007 | —0028 | —0010 } +0025 | —0021 | +0002 —0004 | —0025 +0015 0000 || +0007 | +0006 | —0013 || —0003 111. Variation of the Vertical Component with reference to the Moon’s Hour-Angle.—There are four independent results in Table 54, namely two for the winter lunations, and two for the summer lunations of 1844 and 1845, the others depend on these. In all the four the maximum vertical component occurs between 2 and 4 hours after the moon’s transit of the inferior meridian ; in three cases a secondary maximum occurs at, or shortly after the superior transit,—minima occurring during the intermediate period, from 6 to 8 hours after, and from 2 to 4 hours before, the superior transit; in the winter lunations for 1844, only the principal maxi- mum and minimum are shewn (see the similar case for the horizontal component No. 80), and, as the variations for this group are much greater than for any of the others, it is probable that the difference is due to disturb- ances. See the volumes for 1844, p. 382, where the elimination of the larger disturbances leaves traces of a secondary maximum and minimum. 112. From the means of all the winter lunations in Table 54 The vertical component is a maximum about 2 hours after the moon’s inferior transit. BBP oi senitin eee cine,esonciersetsen minimum.........9 hours after the moon’s superior transit. lvl GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. The means of all the summer Iunations indicate that The vertical component is a principal maximum about 33 hours after the moon’s inferior transit. BOLE BUG HMNSanoC due HEROS ACOACOLDO ADE OA mmimum;.~:..--.0% NOULS:..2.42.002-.-2.2e-sSUpenlotatransiv. apedavoeoddabadasnobantensdac a secondary maximum near the moon’s superior transit. Bere afe seiete eareinare aie octols ec tisieisceceacrmae ele minimum about 5 hours before the moon’s superior transit. This last result serves very nearly for the mean of all the lunations in 1845, and for the mean of all the lunations in 1844, when the larger disturbances have been rejected as in the place cited above. MaAGwNwetic DIP. 113. Observations for the absolute value of the magnetic dip were made with an instrument by Robinson in the years from 1841 to 1849 ; those till May 1843 were made with the instrument on a pillar near the declin- ometer (see Introduction, 1843, p. liv.); from June 1843 till February 1846, the observations were made in a small wooden house erected for the purpose about 19 yards north of the Observatory dip-pillar. The obser- vations after June 1843 were in general very unsatisfactory ; and ultimately, in February 1846, the observa- tions were discontinued (see section Inclinometer, in the Introductions to the various volumes, for details.) In order to determine the annual change of dip, the inclinometer was placed on the original dip-pillar in the Observatory in September 1849 ; previously, it was found, that both needles belonging to the instrument were much disfigured by rust ; the rust was removed as carefully as possible and the needles rebalanced. 114. The following are the results of the observations, which were very satisfactory :— Sept. 284 23h Needle No. 1. Dip =/geloee3 200 G08. dae) Dip = 71° 14-87 2907 2h Needle No, 2. Dip = (1216296 gga. ph Dip = 71° 16-27 115. The dip resulting from these observations differing to a considerable extent from that obtained previously in the dip-house, the inclinometer was removed to that place in order to determine the value of the difference. It was found that the dip obtained on the Observatory pillar, was nearly five minutes less than that shewn in the dip-house. Other observations were made immediately outside the Observatory, on the top, and at the NW. foot of the Observatory hill, which agreed almost exactly with those made on the Observatory pillar. The details of these observations must be reserved for another occasion ; it is believed, however, that the difference found for the first two places of observation is due to the wall of a sunk fence built of trap stones, which passes within about 2 yards of the instrument when in the dip-house, the top of the wall bemg on a level with the surface of the ground. The following then are the méans of all the observations of magnetic dip made with the Makerstoun inclinomete: ; the observations made in the dip-house between June 1843 and February 1846, having been corrected by — 5’. TABLE 55.—Mean Value of the Observations of Magnetic Dip. Dates. Mean Epoch. No. of Position of | Mean of Observations.| Inclinometer. | Observed Dips. | ° , July —Dee. 1841 1841-8 27 Observatorya((t| sete Jan. —Dec. 1842 1842-5 86 Di aa | 23-95 Jan. —June 1843 1843-2 36 I | 22.14 June—Dee. 1843 1843-7 48 | 20-20 Jan. —Dec. 1844 1844-5 67 Doe | 23-69 Jan, —Dee. 1845 1845-5 82 Se | 23-10 Jan. —Feb. 1846 1846-1 12 | 22-40 Oct. 1849 1849-7 4 aa } 16-00 116. The observations made in the years 1841-23 on the Observatory dip-pillar, give for the mean epoch . ° : . : ° fis 1842°5, the mean dip = 71° 24-0; those made on the same pillar 1849-7, give the mean dip = 71° 1670; whence the change in 7°2 years = — 80, or = — I1'11 a year. ANNUAL VARIATIONS FOR THE MAGNETIC Dip. lix 117. The observations made in different azimuths already noticed, render it probable that the dip deduced above is inaccurate from instrumental causes ; the mean dip from observations in all the azimuths was less than that from the observations in the magnetic meridian by upwards of 10’. 118. In order if possible to determine the true dip, the inclinometer belonging to the Royal Society of Edinburgh was obtained, and observations were made with it on the Observatory dip-pillar as follow :— Sept. 254 5» Needle No. 1. Dipi— yale 1138 OX Ns RGM tier ey er AeA Dip = 71° 10°83 $ Mean Dip = 71° 10':36 264 — 274 Needle No. 2. Dip = 71, 8-88 The instrument was not in good order and a considerable time was spent on the observations ; but the results agree very well. Observations with needle No. 2, were also made in the azimuths 30° and 120°, which gave the following values :— By the Formula for both Azimuths. Azimuths 30° and 120°, Dip = 71° 4’-2 By the Formula for single Azimuths. Azimuth 30° Dip enh 9484 Pe: 120° = Dip = 70° 47-7 The observations with the Royal Society’s inclinometer in the magnetic meridian give the magnetic dip about 6’ less than those with the Makerstoun instrument. It cannot be said that the true dip for Makerstoun is yet accurately determined, as the observations with the Royal Society’s inclinometer in different azimuths will scarcely permit the assumption that it is free from instrumental error. 119. The following results are deduced from those already obtained for the horizontal and vertical components * of magnetic force. (See 1844, p. 390.) It may be remarked here, that the epochs for the horizontal component and magnetic dip agree very nearly in every case where both have been determined; maxima of the horizontal component being equivalent to minima of dip, and vice versa; therefore, when investigations have not been made similar to those for the horizontal component for the magnetic dip (such as for the mean difference ‘or disturbance), the law for the former may be assumed for the latter, and the values of the variations of dip in minutes may be ob- tained approximately from the numbers for the horizontal component by multiplying the latter by 1000. 120. Secular Change of Magnetic Dip.—If we assume the secular change for the horizontal component = + 0°001318 (No. 52), and for the vertical component, as deduced from the years 1845-9, = — 0-001055, we find the secular change of dip = — 247; this is considerably greater than that obtained from the obser- vations of absolute dip No. 116; since the secular change for the horizontal component must be near the truth (No. 53), and that obtained for the dip, No. 116, cannot be far from it, it is probable that the secular change for the vertical component is still considerably in error, that in fact the balance needle is still losing magnetism. 121. Effect of Disturbance on the Yearly Mcan.—From the means for the days selected as nearly free from disturbance in the years 1844 and 1845, we find from Nos. 54 and 85, that the yearly mean of magnetic dip deduced from the undisturbed days is less than that from all the observations by 0°15. The effect of dis- turbance, therefore, is to increase the magnetic dip, although the effect on the magnetic declination is nearly zero. (No. 38.) 122. Annual Period of Magnetic Dip.—This result depends chiefly on that for the horizontal component ; adopting the annual period for the vertical component, deduced from the observations for the years 1843-6, as the best representative of that variation, and employing the annual variations for the horizontal compo- nent, deduced from the observations in the years 1843-6, 1842-5, and 1842-7, we obtain the following numbers : TABLE 56.—Monthly Variations of Magnetic Dip, free from Regular Secular Change. March. | April. June. July. Aug. Sept. Oct. Nov. — 0-131 |— 0-167 — 0-101 |—0-110 — 0-263 | —0-161 + 0-102 |+0-207 +0-111 |+0-311 + 0-035 |+0-302 MAG. AND MET. obs. 1845 anp 1846. — 0-256 | — 0-209 — 0-355 | — 0-147 — 0-516 | — 0-278 +0-174 +0-116 + 0-209 + 0-400 + 0-282 + 0-502 +0:331 +0-211 + 0-642 + 0-020 +0-056 +0-199 P lx GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. The variations of each of these groups of years exhibit a law which may be thus stated :—The magnetic dip is greatest near the eqinoxes, and it is least near the solstices, The variations for the years 1842-5 are perhaps least affected by disturbances ; for these years the two maxima have nearly equal values, but the minimum at the summer solstice is greater than that at the winter solstice: in the variations for the years 1843-6 the two minima have nearly equal values, but the two maxima are unequal, the maximum at the autumnal equinox being greatest (See Plate VI.) : and in the variations for the years 1842-7, both maxima and minima are unequal ; the greatest maximum occurring at the autumnal equinox, and the greatest minimum at the summer solstice. The same results are to be obtained for the annual period of the horizontal component, the differences depending upon the amount of disturbance in the different groups of years. 123. When we deduce the monthly means of magnetic dip from the observations of the two component mag- netometers, made on the days selected as nearly free from irregular disturbance, in the years 1844 and 1845, we find the means from all the hourly observations in those years greater (+ ) or less (—) than the former by the following quantities. (See Nos. 57 and 59.) Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. +0158 + 07294 +0°258 + 0"196 —0°037 —0'026 —0°032 +4 0°060 +0088 +0°348 +0150 +0356 The effect of disturbance on the monthly mean magnetic dip is negative in the three months May to July, and is positive in the remaining months. If these means be subtracted from those for the corresponding months in Table 56, it will be found that the annual period from the undisturbed days has the same epochs as that from the disturbed days. (See No. 58.) 124. Annual Variation of the Ranges of the Monthly Mean Variation of Dip—The following are the ranges of the mean variation for each month, from four years’ observations, as obtained from Table 57. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Noy. Dee. LO" Ol f 2 2°06 S20 a S20 nokia 404 -3"88 2°92 2/39) 1°46 1-01 The range of dip was least in February, and in the three months December, January, and February; it was ereatest in July, and in the months from May to August, the range for June being slightly less than for May, July, and August. The following are the ranges of the mean variation, obtained from the observations on the selected days of 1844 and 1846, Jan. Keb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dee. 0°53 0':62 1°85 BHA BYePAS) 3°26 3°04 3°23 oO} ag AOS aS Oe lOs The range of the nearly undisturbed mean diurnal variation is least in January, and it is nearly constant in the months from April to September. (See No. 93.) 125. Variations of the Daily Mean Magnetic Dip with reference to the Moon’s Age—The following num- bers, the means for groups of days from four years’ observations, are obtained from the last column of the first parts of Tables 28 and 45. Moon’s Age. 144164 174208 2ld_24d 254984 294_]4 2a—ga 6i—ga 10¢—13¢ Variations, + 0°069 + 0°147 + 07034 — 0°1387 — 07123 — 0088 + 07012 + 0°085 These numbers shew that the magnetic dip was greatest immediately after opposition, and that it was least immediately before conjunction. 126. Variations of the Daily Mean Magnetic Dip with reference to the Moon’s Declination —The follow- ing numbers, also derived from four years’ observations, are obtained from the last columns of Table 28 and 46. Day after Moon | 974_]a Qa 5a 6i— ga Qa__} a 134— 54 168194 20a_294 oga—_a6a farthest North. J Variations, — 00438 + 0°0038 + 0°072 + 0°004 — 0"°051 — 0027 + 0001 + 0'-038 [t appears therefore, that a minimum of magnetic dip oceurred when the moon was farthest north, another minimum oceurred when it was farthest south, and maxima occurred when the moon was near the equator. This law is exactly the same as that for the annual variations. No. 122. 127. Monthly Variations of the Range of Dip—These and the analogous results for the mean difference cannot be derived from Tables 29, 30, and 46, 47, but require the conversion of all the hourly observations | eee ee oak Wirrwe Wet tpl on Ws { | i DIURNAL VARIATIONS FOR THE MAGNETIC DIP. ]xi into dip, reductions which have not been performed, the laws for the dip however are quite the same as those for the horizontal component, to which we refer. See also No. 141. Diurnal Variation of the Magnetic Dip.—The following Table is deduced from Tables 31 and 48. TABLE 57.—Diurnal Variations of Magnetic Dip for each Month, as deduced from the Regular Daily Observations made during the Four Years 1843 to 1846. March. 0-214 0-773 0-861 0-478 0-567 0-538 0-317 0-696 1-344 1-759 2-060 1-824 1-369 0-693 0-336 0-134 FP ODCOONOouFrwndr © — — 128. The following are the approximate epochs of maxima and minima in apparent time as deduced from Table 57, distinguishing the epoch of the principal maximum by + and of the principal minimum by — , ” Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. h. m. h. m. h. m. h. m. h., m. h. m. hm h. m h. m. h. m. h. m. h. m. Max. 2220 +22 5 422 5 +2212 22 5 2130 2145 21 20 +2155 42215 +2240 +422 55 Min. 310 — 230 - 350 —~ 545 545 640 555 5 25 — 4 35 8 15 5 55 5 55 Max. +14 0 12 46 14 0 14 30 aac 3a aot 316 14 35 12 25 10 30 i115 Min. —17 40 —-18 40 17 50 Li 0 dou 560 506 O00 75 -16 25 -1815 —-18 15 These epochs are very nearly the same as those obtained for the horizontal component No. 69. The diurnal variation of magnetic dip at Makerstoun has only one maximum and minimum in the four months May to August, and it has two maxima and two minima in the remaining eight months, The morning minimum near 6" a.m., is the principal minimum in the four months October to January, in February the two minima are equal ; in the other months the principal or only minimum, occurs near 6" p.m.; the principal maximum of dip occurs in each month with the exception of January near 10> a.m. It is only in the four winter months November to February that the 25 a.m, maximum is well marked. The variations of the epochs of maxima and minima will be found with most accuracy from Table 58, which contains the diurnal variations for groups of months. Ix GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. TABLE 58.—Diurnal Variations of Magnetic Dip for different periods, deduced from Table 57. Mak. Mean Time. | March. : March | Twelve April. : Sel fo | Months. Aug. | RKP OOONODUABWNHe OCC — 129. The approximate epochs of maxima and minima in apparent time, from Table 58, are :— Dec. Jan. Feb. March, April. May, June, July, Aug. Sept. Oct. Nov. Maximum, +105 20™ a.m. +105 15 a.m. 9h 50™ aM. 9h 35™ A.M. +10h 0™ a.m. Minimum, 2h 50™ p.m. —5> 0™ p.m. 6 20™ p.m, 5» 30™ p.m. — 5) 35™ p.m. Maximum, 2h §™ a.m. Qh 10™ a.m. see cee cone 12 55" aca Minimum, — 6P 5m a.m. 5h 45™ a.m. tet tee cee eee ees settee eee cee ees 4h 55™ aM. The principal maximum, near 10" 4.m., oceurs earliest in July and August, and latest in December to Feb- ruary: the afternoon minimum occurs earliest in the three winter months, and latest in May and June: the other maximum and minimum occur earliest in the months September to November. (See the Continuous Curves, Plate IV., where it is to be remembered that the apparent minima of the curves are the maxima of dip.) The following Table contains the diurnal variations for the days selected as nearly free from intermittent dis- turbance. 130. The approximate epochs of maxima and minima in apparent time for the undisturbed diurnal varia- tions, are as follow :— Dee. Jan. Feb. March, April. May, June. July, Aug. Sept Oct. Nov. Maximum, +102 45™ a.m, +10 20™ a.m. 9h 50™ AM. 9h 45™ ain. +105 15™ a.m. Minimum, 5) 95m pw. — 7h 5m p.m. 6% 30™ pm. 72 Om p.m. — 65 45™ pm. Maximum, Lh 35™ a.m, SE DOM a aig mpidmeete cece sind ofl) aeeeeoeeeeeee ale 15 55™ a.m. Minimum, — 6 25™ a.m. BE LSM ASM) pape ae aaied clricaeekemecek ae 5h 5™ aM. In the undisturbed, as in the disturbed variations, the principal maximum occurs earliest in July and August, and latest in December to February ; but, unlike the disturbed variations, the afternoon minimum ocewrs latest near the equinoxes ; it occurs rather earlier at the winter than at the summer solstice. (See the Dotted Curves, Plate IV.) DIURNAL VARIATIONS FOR THE MAGNETIC Dip. Ixiii TABLE 59.—Diurnal Variations of the Magnetic Dip for different Periods, deduced from Days selected as free from Irregular Disturbance in the Years 1844 and 1845. Six Months. March. anes Twelve | : Sept. April. Nose ae Months. | Feb. — 0-362 “3 — 0-098 — 0-260 -221 || —0-035 —0-115 “ — 0-041 — 0-034 034 “ —0-112 — 0-068 % — 0-198 —0-182 . — 0-289 || — 0-233 — 0-070 | +0-341 || + 0-700 +0-932 +0-781 + 0-487 +0-073 — 0-084 || —0-129 — 0-207 | —0-297 || — 0-367 — 0-314 || —0-258 KH COODONOAUNK WHE OS a TABLE 60.—Differences of Disturbed and Undisturbed Diurnal Variations of Magnetic Dip, as deduced from Tables 58 and 59, exhibiting the Effect of Irregular Disturbance on the Hourly Mean Position. Six Months. March. : Sept. Nar | Twelve { April. : ae || +6 Months. | | Feb. | +0-079 — 0-013 | +0-1356 — 0-041 — 0-093 — 0-120 —0-113 — 0-019 — 0-030 + 0-068 + 0-023 + 0-001 SBP COOOoOnNaurrhwnNnreo& — — + 0-067 ' i MAG. AND MET. oBs. 1845 anv 1846. q lxiv GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 131. Diurnal Variation of the Effect of Disturbance on the Magnetic Dip—A remark, similar to that made No. 72, with reference to the horizontal component, will apply to Table 60. The conclusions from this Table are as follow :— lst, The greatest effect of disturbance in increasing the magnetic dip occurs In Dec, Jan. Feb. March, April. May, June. July, Aug. Sept. Oct Nov. 1225 a.m. 13> a.m. h es 95 a.m. 92 P.M. About { Ope us Erna 11" p.m. and 832 a.m. Ga cae tot pan There are two epochs in May and June at which the positive effect of disturbance is a maximum, and there are two similar epochs for each group of months, for one of which either the positive effect is a secondary maxi- mum, or the negative effect is a minimum ; the times of these are given above, in the second line. 2d, The greatest effect of disturbance in diminishing the magnetic dip occurs In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Noy. 4h pm. 45 p.m 5h pm 65 a.m, and 3} p.m. oe i 3h a.m. and 3" pm. a { - 6" a.m. 45 aM. 12h pu 32 end 3" Pi In the winter groups there are two nearly equal maxima for the negative effect of disturbance, and in each of the others there is, besides the principal maximum, either a secondary maximum of the negative effect, or a minimum of the positive effect ; the times of these are given above in the second line. 3d, The effect of disturbance upon the hourly mean magnetic dip is zero In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 104 a.M., 7» p.M., 34 A.M. 7» a.M., 105 a.M., 75 P.M. Noon, 94 p.m, 1) p.m., 82 P.M. 10® a.M., 65 p.m, 12 a.m. The best defined hours are those from 6" p.m. to 94 p.m., and from 10" a.m. to 1® p.m. See No. 76 for the probable law of mean disturbance for the magnetic dip, substituting for positive distur- bance of the horizontal component, negative disturbance of dip, and vice versa. TABLE 61.—Variations of the Magnetic Dip with reference to the Moon’s Hour-Angle for the Winter and Summer Lunations, and for all the Lunations of the Years 1844 and 1845. Winter Lunations. Summer Lunations. All the Lunations. Moon’s 1845, Mean. 1844, 1845. Mean. 021 -017 —-045 -028 -037 154. | -092 -030 -071 || —-051 -004 -006 -006 -010 -170 | -100 -027 031 O14 031 096 || —-101 O15 075 || —-115 004 042 || +-026 036 085 || +-080 —-006 -106 || +-123 -042 057 || +-066 + | } _ bo | =) S o | | eae | fs SS) (SS) COoOWOWW DwWwoQwr Pee seat Sie | _ our oO ap ae lor sl] S S o | o Ges; ww a peer | os ay on eS 132. Variations of the Magnetic Dip with Reference to the Moon’s Hour-Angle—The four independent columns of Table 61, give results quite analogous to those obtained for the horizontal component of magnetic force, No. 79: the results for the winter lunations of 1844, and for the summer lunations of both years, agree very nearly with that for the mean of both years in the last column of Table 61,—which may be stated as follows :— The magnetic dip is a minimum about 1 hour after the moon's inferior transit. se maximum about 3} hours before the moon’s superior transit. minimum about 23 hours after the moon’s superior transit. maximum about 8 hours after the moon's superior transit. ANNUAL VARIATIONS OF THE TOTAL MAGNETIC FORCE. lxv The winter lunations for 1844 agree with this result, in having a minimum immediately after the inferior transit, but not otherwise: this difference, it is considered, is due to disturbances. (See No. 80.) ToTAL MAGNETIC FORCE. 133. Absolute Value of the Total Magnetic Force.—The absolute value of the total magnetic force de- duced from the value of the horizontal component, and the magnetic dip, as in No, 81, is as follows :— Total magnetic force at Makerstoun for the mean epoch 1845 = 10:5267. 134. Secular Change of the Total Magnetic Force.—The determination of this depends chiefly on the balance magnetometer, and it is probable that the secular change from that instrument is not to be trusted (No. 84) ; indeed it is probable that the total force remains nearly constant, and this is the more likely the nearer the secular change deduced for the magnetic dip is considered to be to the truth. (See No. 116.) 135. Effect of Disturbance on the Yearly Mean Value of the Total Magnetic Force-—By Nos. 54 and 85, we find that the yearly mean deduced from the selected undisturbed days, is greater than that obtained from all the observations by 0:000045, the total force here and in the following discussions being considered equal to unity. 136. Annual Period of the Total Magnetic Force.—This result depends chiefly on that for the vertical com- ponent and is entitled to the same weight. The following are the variations of the monthly means of the total force, deduced from the observations of the balance and bifilar magnetometers for the four years 1843-6. (See Nos. 56 and 87.) Prefix. Jan. Feb. March. April. May. June. July. Aug. . Sept. Oct. Nov. Dee. 0:000 | +099 —013 —074 —075 —034 +120 +052 —001 —049 —087 +011 +048 From these numbers, the total magnetic force at Makerstoun is a maximum about the solstices, and a minimum immediately after the equinowes (See Plate VI.) 137. The monthly means deduced from all the hourly observations in 1844 and 1845, were greater (+ ) or less (—) than those obtained from the days selected as nearly free from disturbance by the following quantities. (See Nos. 57 and 89.) Prefix. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dee: 0000 | —069 +001 —106 —060 —062 —003 —037 —061 —052 —078 —008 +002 The effect of disturbance on the monthly mean was nearly zero in the months of February, June, and December, and it was greatest in March and October. When these numbers are subtracted from those in No. 136 it is found that the annual period obtained from the undisturbed days in each month, has the same epochs as that obtained from all the days. 138. Annual Variation of the Ranges of the Monthly Mean Diurnal Variation of the Total Magnetic Force. The following are the ranges of the mean diurnal variation for each month, as obtained from Table 62, deduced from four years’ observations. Prefix. | Jan. | Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dee. 0-000 | 319 291 612 821 701 546 663 738 716 521 443 298 The diurnal range of the total force was least in the three months, December, January, and February, and it was greatest in April and August: the ranges for March and September were greater than the range for June. The following are the ranges of the mean variations obtained from the selected days of 1844 and 1845. fBrefix. 0-000 Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dee. 112 151 277 398 489 449 448 389 409 321 176 154 The range of the nearly undisturbed mean diurnal variation was least in January 1844—5, and it was ) greatest in May, but it is probable that the range is nearly constant while the sun is north of the equator, and that the differences exhibited here are due to the greater or less amount of disturbance remaining in the selected days. (See Nos. 92 and 93.) 139. Variations of the Daily Mean Total Magnetic Force, with Reference to the Moon’s Age.—The fol- Ixvi GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. lowing quantities, the means for groups of days from four years’ observations, are obtained from the last column of the first parts of Tables 28 and 45. (Prefix 0-000.) Moon’s Age, 144162 174204 214244 25a__984 2944 Qa— 5a 6h—ga 104134 Variations, — 024 + 007 + 024 + 011 +001 + 008 + 009 — 034 The total force, therefore, is least near opposition, and it is greatest near the quadratures. (See No. 96, 1st.) 140. Variations of the Daily Mean Total Magnetic Force, with Reference to the Moon’s Declination— The following variations are derived from the final columns of Tables 28 and 45. (Prefix 0-000.) Day after Moon faceieat ee 274—14 24—54 64—ga ga—_}ga 134154 164194 204294 ©=-9ga_9ga Variations, + 024 — 004 —016 — 010 25. (Oi by/ — 004 — 001 — 005 These variations indicate that the total force is a maximum when the moon is farthest north, and also when it is farthest south, and that is a minimum between these epochs. This result is quite analogous to that for the sun’s position in declination (see No, 136). In both cases, the total force is greatest when the body (sun or moon) has its greatest north and south declinations, and it is least during the intermediate positions, or when the body is near the equator. 141. Monthly Variations of the Range of the Total Force.—This law is the same as that for the vertical component (No. 97), but has not been deduced for the total force, for the reason given No. 127. It may be stated generally, whether the position of the sun or the moon be under consideration, that the diurnal range of all the magnetic elements is greatest when the body is rather north of the equator, and that the range is least when the body is farthest south and farthest north. It has been found, generally, that when undisturbed mean variations are examined, the diminution of diurnal range, when the sun is most northerly, disappears, and it is probable that the same would be true with respect to the moon; the excess of range, when the bodies are near the equator, being due to the greater amounts of disturbance which occur at these times. (See No. 23.) TABLE 62.—Diurnal Variations of the Total Magnetic Force for each Month, as deduced from the Regular Daily Observations made during the Four Years 1843 to 1846. March. 0051 0012 0000 0005 0080 0151 0200 0190 0132 0080 0024 0038 0105 6229 0349 0485 0517 0701 0699 | 0676 | 0547 | 0385 0289 | | 0196 DiuRNAL VARIATIONS FOR THE ToTAL MaGnetic Force. Ixvul 142. Diurnal Variation of the Total Magnetic Force.—Table 62 has been computed from Tables 31 and 48. The following are the approximate epochs of maxima and minima in apparent time, distinguishing those of the principal maximum by +, and of the principal minimum by —. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. h. m. ins. 15. eh hey. h. m. hens h. m. h. m. h. m. iheaems hsm. h. :m. Max. +535 +5 0 +5 5 +555 +545 +630 +535 +535 +455 +340 +625 + 6 20 Min. SA 4 0 —1Se459) — 130) = 4°35 14 15 TAvA0 4S oa Si Sson ea Onlo) — 12 45-14 45 Max. 19 5 19 15 19 30 19 0 18 40 18 35 18 30 18 35 18 50 19 45 18 50 19 5 Min. DY (0) 21 55 22 30 D2EAO we — 22405 — on Oy +— 22045 22 20 DAL 8 5) 22°35 22550 — 22) 15 The principal maximum of the total magnetic force occurs between 35 40™ and 65 30™ p.m. in each month of the year; it occurs latest in June and November ; it occurs earliest in February and March, of the first six months, and in October and_September of the last six months of the year, The principal minimum occurs near 2" a.m. in each month, with the exceptions of June and July, in which months it occurs near 11" a.M.; in May, November, and December, the two minima are nearly equal. The secondary maximum occurs between 624 and 73 a.m., and it is best marked in the months of March, April, and May, August, and Sep- tember. TABLE 63.—Diurnal Variations of the Total Magnetic Force for Different Periods, deduced from Table 62. Six Months. Mak. Dec. March. May. July. Sept. s Twelve oe | oli April. June Aug. oe Saas ee Months: Feb Aug. 2 h. m. || 0 0:00 0:00 0-00 0-00 0-00 0-00 o 12 13 || —0091 | —0236 | —0123 | —0154 | —0180 —0135 | —0171 — 0154 SUS —0094 | —0249 | —0168 | —0190 | —0192 —0143 | —0202 —0173 14 13 —0135 | —0288 | —0180°| —0218 | —0198 —0166 | —0229 —0198 15 13 —0109 | —0207 | —0166 | —0197 | —0182 —0145 | —0190 — 0168 16 13 || —0085 | —0180 | —0124 | —0158 | —0169 —0127 | —0154 —0141 WAS —0064 | —0125 | —0089 | —0148 | —0132 —0098 | —0121 —0110 18 13 —0045 | —0067 | —0059 | —0117 | —0096 —0070 | —0081 — 0076 19 13 — 0037 | —0046 | —0065 | —0120 | —0075 — 0056 | —0077 — 0067 20 13 —0041 | —0066 | —0116 | —0160 | —0085 —0063 | —0114 — 0089 PAN ANS} —0061 | —0111 | —0178 | —0202 | —0114 —0087 | —0164 —0126 22 13 —0075 | —0151 | —0230 | —0223 | —0124 —0099 | —0201 —0151 23) 13 —0050 | —0148 | —0230 | —0219 | —0095 — 0072 | —O0199 — 0136 0 13 —0021 | —0102 | —0163 | —0148 | —O0001 —0011 | —0138 — 0074 eS +0033 0000 | —0060 | —0021 | +0098 +0065 | —0027 +0019 4 1133 +0085 | +0130 | +0051 | +0106 | +0184 | +0134 | +0096 | +0115 8) ils} +0133 | +0236 | +0167 | +0258 | +0285 +0209 | +0220 || +0214 4-13 || +0144 | +0305 | +0256 | +0361 | +0313 +0228 | +0301 +0264 a 13 +0152 | +0408 | +0358 |-4+0441 | +0313 +0232 | +0402 || +0317 6 13 +0161 | +0399 | +0373 | +0441 | +0284 | +0222 | +0404 | +0313 i 13 +0142 | +0325 | +0356 | +0378 | +0209 | +0175 | +0353 + 0264 8 13 +0107 | +0210 | +0264 | +0265 | +0114 || +0110 | +0246 | +0178 9 13 +0056 | +0074 | +0141 | +0097 | +0020 +0038 | +0104 | +0071 10 13 —0020 | —0045 |} +0048 | +0018 | —0055 —0037 | +0007 — 0015 i 13 —0074 | —0074 | —0038 | —0096 | —0121 —0097 | —0069 — 0084 143. The means for groups of months having been obtained, as for the other magnetic elements, we find the approximate epochs for the mean diurnal variation in apparent time as follow :-— Maximum, Minimum, Maximum, Minimum, Dec. Jan. Feb. +65 10™ p.m. —2h 10™ a.m. 7h 10™ ao. 9h 55™ aM, March, April. + 5b 95m p.m, — 25 10™ a.m. 7h 5M a.m, 102 35™ a.m. MAG. AND MET. oss. 1845 anp 1846. May, June. + 5h 45™ p.m. 15 45™ a.m. 6» 35™ a.m. —10® 45™ a.m. July, Aug. + 5 ooh 6h — 102 35™ P.M. 10™ a.m. 35™ A.M. 35™ A.M. Sept. Oct. Nov. + 44 50™ p.m. Qh 20™ a.m. 7h 35™ a.m. 10 20™ a.m. Tr Ixvill GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. In the disturbed diurnal variation of total magnetic force, the principal maximum occurred latest in the quarter December to February, and earliest in the quarter September to November: the epoch of the after-midnight minimum varied little, being slightly nearer midnight in May and June than in the other groups ; the secondary maximum occurred earliest in May and June, and latest in September to November ; and the forenoon minimum occurred earliest in the quarter December to February, and latest in May and June. In May and June, therefore, the one minimum occurred nearest noon, the other nearest midnight. (See the Continuous Curves, Plate V.) TABLE 64.—Diurnal Variations of the Total Magnetic Force for Different Periods, deduced from Days selected as free from Irregular Disturbances, in the Years 1844 and 1845. a ae = ae Six Months. | aes ec March. | May. July. opt: || Twelve ae a April. chee Aug oe || Sept. to | March ] Months. Hebiea |g. vo Auge h; m. || 0-00 0-00 0-00 0-00 0-00 0-00 | 0:00 || 0-00 12,13 —0016 | —0029 | —0031 | —0032 | —0051 — 0033 | —0031 | —0034 13 13 — 0037 | --0043 | —0039 | —0047 | —0059 | —0048 | —0043 ] — 0045 14 13 | —0041 | —0027 | —0034 | —0049 | —0049 — 0045 | —0037 | —0040 15 13 —0038 | —0023 | —0014 | —0027 | —0042 | —0040 | —0021 — 0030 16 13 — 0031 —0025 | +0011 | +0003 | —0032 —0031 | —0004 | —0018 gus — 0022 | —0004 | +0021 | +0010 | —0022 —0022 | +0009 | —0007 18 13 — 0022 | +0010 | +0012 | +0009 | —0023 — 0022 | +0010 — 0006 19 13 — 0023 | +0009 | —0016 | —0030 | —0024 | —0023 | —0012 || —00i8 20 13 — 0025 | —0019 | —0077 | —0103 | —0063 | —0044 | —0066 || —0055 21 13 —0045 | —0080 | —0162 | —0169 | —0107 | —0076 | —0137 || —0106 22) 13. —0061 | —0151 | —0229 | —0204 | —0146 —0103 | —0195 | —0149 23 13 —0056 | —0182 | —0251 | —0218 | —0125 — 0090 | — 0217 | —0154 0 13 —0028 | —0181 | —0200 | —0176 | —0089 | —0058 | —0186 || —0122 1 13 +0017 | —0100 | —0105 | —0084 | —0002 | +0007 | —0096 || —0044 23. +0053 | —0005 | —0024 | +0013 | +0075 | +0064 —0005 | +0029 3) 13 +0071 | +0069 | +0064 | +0108 | +0126 | +0098 | +0080 | +0089 413 | +0075 | +0113 | +0139 | +0157 | +0152 | +0113 ) +0136 | +0125 5 13 || +0069 | +0143 | +0201 | +0196 | +0140 | +0104 | +0180 | +0142 6 13 +0059 | +0145 | +0215 | +0197 | +0126 | +0092 | +0186 | +0139 Feuike} +0048 | +0137 | +0199 | +0176 | +0103 | +0075 40171 +0123 8 13 +0039 | +0105 | +0160 | +0145 | +0086 | +0062) +0137 +0099 9 13 +0032 | +0080 | +0106 | +0086 | +0051 | +0041 | +0091 | +0066 10 13 |} +0016 | +0050 | +0045 | +0042 | +0016 | +0016 | +0046 | +0030 11 13 —0014 | +0008 0000 | —0004 | —0036 | —0025 | +0001 —0012 144. When we consider the diurnal variation, as deduced from days selected as nearly free from intermit- tent disturbance, and as exhibited in Table 64, and in the dotted curves, Plate V., we find the approximate epochs in apparent time as follow :— Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. Maximum, + 42 0” p.m. + 5> 40™ p.m. + 6h Om p.m. + 5h 35™ p.m. + 45 15™ pM, Minimum, 1» 40™ a.m. 1» 10™ a.m. 1h 30™ a.m. 1h 40™ a.m. 15 95m am, Maximum, 5h 35™ a.m. 6h 45m a n, 5h 15™ a.m. 52 35™ a.m. 6h 90m an, Minimum, —10" 35™ a.m. —11" 45™ a.m. — 10" 55™ a.m. —10® 55™ am. —105 30™ aan The undisturbed diurnal variation of the total magnetie foree ditlers considerably from that affected by dis- turbances, as may be seen at a glance in Plate V.; the whole variations of the epochs of maxima and minima, with season, are different from those obtained, No. 148. In each group of months, the forenoon minimum is the principal, and the after-midnight minimum is quite secondary. The principal maximum occurs earliest in winter, about 4" p.m., and latest in May and June, about 6" p.a.; the principal minimum occurs earliest in the six months, September to February, and latest in March and April: the secondary maximum oceurs nearest noon, and the secondary minimum nearest midnight, in the equinoctial months. DIURNAL VARIATIONS FOR THE TOTAL MAGNETIC FORCE. Ixix TABLE 65.—Differences of Disturbed and Undisturbed Diurnal Variations of the Total Magnetic Force, as deduced from Tables 63 and 64, exhibiting the effect of Irregular Disturbance on the Hourly Mean Positions. Six Months. | | Sept. March. | May. aI ous | : | Twelve April. | June. Noes I | Months. | — | 0°00 “00 0: |, 0:00 | —0129 | | | —0120 —0133 | 5 | | —0128 —0149 || : | —0158 —0140 | ; —0138 —0137 | — 0123 —0110 || —0103 — 0073 || 48 | || —0070 —0051 || | 55 || —0049 — 0022 | — 0034 | —0007 | 27 || —0020 | +0022 | — 0002 | +0030 | | | +0018 | +0088 | : | +0048 +0100 | + 0063 | +0109 +0086 | +0159 +0125 +0161 } +0139 | +0173 2 || +0175 +0158 || é +0174 | +0106 | | +0141 | +0028 +0079 | —0031 || +0005 | —0071 | | —0045 2) —0085 | | —0072 ROCODNMRAAWNHO — 145. Diurnal Variation of the Effect of Disturbance on the Total Magnetic Force, The remark made No. 102, for the vertical component, will apply also to the following conclusions obtained from Table 65. 1st, The greatest effect of disturbance in increasing the total magnetic force occurs In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 6» 30™ p.m. 5 30™ p.m. 65 15™ p.m, 55 40™ p.m, 5> 10m p.m. The hours, it will be seen, agree very nearly with those found as the epochs of the maximum total force in the disturbed diurnal variation. The maximum positive effect of disturbance on the total force, occurs latest near the solstices and earliest near the equinoxes. 2d, The greatest effect of disturbance in diminishing the total magnetic force occurs In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. About 2h O™ a.m. 2h 15™ am. 3h OM a.m. 2) 45™ aM. 25 10™ am. These hours are nearly the same as those for the after-midnight minimum of the diurnal variation; the difference is greatest in the summer months when the maximum negative effect occurs latest. 3d, The effect of disturbance on the total magnetic force is zero In Dec. Jan. Feb. March, April. May, June. July, Aug. Sept. Oct. Nov. ont 108 45™ a.m. 10° 15™ a.m. 10® 10™ a.m. 115 15™ a.m. 9h 45™ a.m. ee { gh 40m p.m. ghjom pw, 108 15™ pM. 9h 30m pm, 8 45m p.m. The one of these epochs is nearly the same as that of the principal minimum in the undisturbed diurnal varia- tion ; the other occurs about twelve hours after. - ’ Ixx GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. TABLE 66.—Variations of the Total Magnetic Force with reference to the Moon’s Hour-Angle for the Winter and Summer Lunations, and for all the Lunations of the Years 1844 and 1845. H Moons Summer Lunations, All the Lunations. Hour- Angle. : 1845. 3 : L4, 1845. Mean. . | sn pe ayaGy Mean. m. 0-000 0 Hy 0000 0:000 0 000 +011 +015 25 +025 § +030 || +012 20 — 046 +020 +005 15 —031 +001 —011 10 — 039 —036 — 035 | 000 +002 — 004 +030 +020 | +006 +042 +027 +024 +045 —003 +017 +024 — 028 || —009 —015 — 039 — 022 -—031 — 006 ~ 000 146, Variation of the Total Magnetic Force with Reference to the Moon’s Hour-Angle.—Of the four indepen- dent results in Table 66, that for the winter lunations of 1844 has the greatest range, and only one maximum and minimum, the maximum occurring about 2 hours after the moon’s inferior transit, and the minimum about 23 hours after the superior transit : the three other results shew two maxima and two minima as follow :-— A maximum from 2 to 4 hours after the moon’s inferior transit. A minimum from 4 to 24 hours before the moon’s superior transit. A maximum from 0 to 2} hours after the moon’s superior transit. A minimum from 6 to 8 hours after the moon’s superior transit. In the mean of all, as shewn in the last column of Table 66, the first minimum and second maximum noted above, are scarcely visible, owing to the effect of the great range of the exceptional result for the winter lunations of 1844. The epochs from the means of all are— The maximum of total force 23 hours after the moon’s inferior transit. ASSMInIM UM eee eee Dihourszbefore. ©........... superior transit. INS ikea hinders Keveeyaaecbodos TL CACM PEI err. erin cistciexeicsere superior transit. The minimum ............... S#hourshatters --..asc cee superior transit. It is probable that the mean of all the lunations is vitiated by the winter lunations of 1844, and that the epochs given above for the remaining lunations of the two years are near the truth. COMBINED MOTIONS OF THE MAGNETIC NEEDLE. 147. Motions of the North End of a Magnetic Needle supposed freely suspended in the direction of the Magnetic Force.—These motions have been represented in Plates VI.—VIII. by projecting the variations of dip, given in the previous Tables, as ordinates to the abscissee deduced from the variations of declination for the same epochs multiplied by the cosine of the dip (=0-32). As great care has been bestowed on the determination and veri- fication of the coefficients of reduction for the bifilar and balance magnetometers, upon which the element of dip depends, it is conceived that considerable confidence may be placed in the accuracy of these figures as re- presentatives of the motions of the north end of a needle supposed freely suspended in the direction of dip at Makerstoun. No attempt has been made in these discussions to introduce theoretical views, but a consideration of the figures in the Plates will probably show the futility of many of the theories brought forth to explain the motion in declination, 148. Annual Motions.—The annual motion deduced from the observations of the three magnetometers for the four years 1843-6 is shown in figure A, Plate VI. In order to exhibit a more symmetrical form of the annual COMBINED MOTIONS OF THE MAGNETIC NEEDLE. Ixxi motion, the magnetic dip, deduced from the observations of the bifilar magnetometer for the years 1842-5 and the balance magnetometer for the years 1843-6, has been employed to construct figure B ; the same declination being used as in figure A. For both figures the monthly mean values for the three magnetometers have been obtained from the curves (Plate VI.) passed freely through or among the projected points. 149. From near the vernal till the autumnal equinox the annual motion forms the half of an ellipse whose major axis, passing at the vertex through June, makes an angle of about +11°in figure A and of + 16° in figure B with the projection of the magnetical meridian. At the autumnal equinox the north end of the needle again ascends till the winter solstice, after which it descends till the vernal equinox. In its descent, the north end of the needle having crossed its previously ascending path, it forms a loop which, when untwisted and continued downwards from the equinoxes, completes the ellipse ; the portion formed by the loop having almost exactly the same perimeter as that regularly formed when the sun is north of the equator ; the completed portion is indi- cated by dotted lines in figures A and B. It does not seem improbable that in southern latitudes the figure will be inverted, and that it will be a simple ellipse near the equator. 150. Monthly Motions.—The motion corresponding to the moon’s varying phase has not been projected, chiefly because of the irregularities still existing in the result of the four years’ observations for the magnetic declina- tion, the epoch of minimum being ill-determined ; it is conceived that the figure is a simple ellipse with its major axis in the astronomical meridian, the northern extremity being at conjunction, the epoch of minimum dip, and the southern extremity at opposition, the epoch of maximum dip ; this, however, is doubtful. 151. The motion for the moon’s position in declination has been obtained in the following manner :—Hav- ing first projected the means of magnetic declination for cach three days of the moon’s position in declination, as obtained from the Tables for the years 1843-6, the day after the farthest northerly position being the abscissa, a curve was passed freely among the points ; the values of the ordinates at the points of intersection by the curve were then taken as the interpolated values of magnetic declination for the corresponding abscissx : a similar operation was performed for the magnetic dip. In both cases very satisfactory curves, agreeing nearly with the true points, were obtained. These values are projected in figure C, Plate VI. From this figure the north end of the dipping-needle commences its ascent about two days after the moon is north of the equator, attains its highest point about two days after the moon is farthest north, and afterwards it descends till the moon is again near the equator; thus forming a figure like a portion of an ellipse with its vertex about one day after the moon is farthest north, the major axis making an angle of about — 30° with the magnetic meridian. It will be remarked that so far this motion is quite similar to that for the sun’s position in declination, with the exception of the axis of the figure being on the opposite side of the magnetic meridian ; when we trace the figure farther the analogy still subsists ;—as the moon proceeds south of the equator the north end of the needle again ascends till the moon is farthest south, thereafter descending, and, in crossing its previously ascending path, a loop is formed lying partially out of the principal figure, as in the case of the annual motion. 152. The correspondence of the two results gives a great weight to the accuracy of both ; this will be more evident when it is remembered, that the whole motion of the dipping-needle for the moon’s varying declination is included by a small circle with a diameter of little more than one-tenth of a minute of space, and, that no obser- vation in the sixty thousand employed for this result has been rejected, however greatly affected by disturbance ; although the graphic interpolation to remove slight irregularities may be considered an equivalent operation. 153. Diurnal Motions.—The monthly mean diurnal variations for the magnetic declination and magnetic dip in Tables 12 and 57, still present irregularities, especially from 10" p.m. till 44 a.m., the hourly positions for this time depending on only two years’ observations. For this reason, the values from these Tables having been projected, curves were passed freely among the points, and the interpolated ordinates thus formed, were taken for the projections in Plate VII.: the interpolated quantities differ very little from the actual values, and this is especially the case for the summer months. 154, The diurnal motions for the 4 winter months November to February, are of the same class, and they differ considerably from those for the other months (see Plate VII.) ; in each of these months the motion consists of a figure of two closed loops: the north end of the needle moves eastwards with little change of dip from about 1 p.m. till 9" or 105 p.m., after which it turns westwards, and begins to ascend about 4" a.m., crossing near its position at 6" p.m., thus forming an eastern loop, which is small compared with the western loop, excepting in December. After 6" a.m., the north end of the needle having moved a little westwards, again descends, crossing a second time the afternoon track near 5" p.m., still moving westwards, it ascends about 11 4.m. till it meets the position of 1" p.m., thus completing the western loop. The eastern loop is not formed in March, the north end of the needle not rising sufficiently high to cross the afternoon track. The change in the figure from February to March is very great ; in April and May the remains of the eastern loop are still visible, but in June and July its position is indicated by a simple inflection in the figure ; in August and September the germ of the eastern loop becomes more distinct, and in October the loop is actually formed. The transition in form from autumn to winter is quite gradual, unlike that from winter to MAG. AND MET, oBs. 1845 anp 1846. $ Ixxu GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. spring. In the winter months, the principal or western loop is formed by the motion from 8 a.m. till 5® p.m, ; in the months from April to August, three-fourths of the whole diurnal motion occur between 6" a.m. and 6" p.m., the remaining fourth forming a slightly inflected side to each of the figures: it is this side which is gradually twisted up to form the eastern loop of the winter months. The figures for means of groups of | months, as in Tables 13 and 58, have been projected in Plate VIII. on a larger scale, the diurnal mo- ~ | | tions from the days selected as nearly free from irregular disturbance have been projected with dotted outlines along with the others. In these figures the actual values in Tables 13, 14, 58, 59 have been employed. In the winter months the undisturbed diurnal variation presents a series of convolutions instead of the eastern loop, and in the other months the general form of the figures is not much altered. 155. It is evident that no proper comparison can be made of the areas of these figures, on account of the involved forms in the winter months; the areas, however, of the figures from April to August, differ very little, * ; 156. Perimeters of the Figures.—The twisting of the perimeters, which renders a comparison of the areas of little value, does not appear to affect the length of the motion, and this therefore seems a fair subject for ex- amination. The following are the values of the angular motion, or length of the perimeter, for each month, as obtained approximately from Plate VII. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Noy. Dec. 5°60) 6216 9/-22 12/18 12/04/1200) V1-56 » 11764, 1 LOCA Siti OGiemmiie 22 momen December and January shew the least perimeters, April, May, and June, the greatest, though the perimeters for the months from April to August are nearly constant. 157. The following are the approximate perimeters of the five independent figures of Plate VIII. :— Dec.—Feb. March, April. May, June. July, Aug. Sept.—Nov. Mean of all, 6°19 11.58 11-88 11:92 9-04 Mean of undisturbed days, 4/34 9’°86 10’°68 117-28 7-76 158. Hourly Angular Motions.—Having obtained the approximate motion from hour to hour for each of the monthly figures of Plate VII., we find that, on the whole, they follow nearly the same law, that indicated in the following numbers, which are the means of the motions from the 12 separate months, and from other groups of months. TABLE 67.—Mean Angular Motions, from Hour to Hour, of the north end of a Needle supposed freely suspended in the direction of the Magnetic Force, as obtained (1.), from the Monthly Figures of Plate VII. (2.), from the 5 Independent Continuous Figures of Plate VIII. ; and (3.), from the 5 Independent Dotted Figures of Plate VIII. Means from | Means from Time. “5 5 5 | 16 ie eee beet Figures. Continuous) Dotted WER rates: Continuous Dotted Figures. | Figures, S Figures. | Figures. h h. , 12—13 0-19 0-10 0-20 13—14 +23 10 20 14—15 | +25 14 16 15—16 +22 18 25 16—17 +24 24 23 17—18 +25 23 24 18—19 237 28 38 19—20 58 bys} 595 20—21 ‘61 58 63 21—22 -69 76 69 22—23 91 85 88 23— 0 -70 67 73 * Tt may not be unimportant to remark here, that the processes usually adopted in order to determine the epochs of maxima % and minima for the separate elements of declination and dip, are not strictly accurate; and that is the case whether the process be ‘i one of interpolation from graphic projection, where the time is the abscissa, or one of computation, where the variable is a fune- a tion of the hour angle. This is evident, when we examine the figures in Plates VII. and VIIL., where the dip and declination are 2 the co-ordinates. The error, however, will not affect any of the comparative conclusions for these elements in the previous pages. | A similar exception may be taken to the accuracy of comparisons of areas of declination curves, where time is the abscissa. LS i ys ee COMBINED MOTIONS OF THE MAGNETIC NEEDLE. Ixxiit 159. These numbers give the following curious result ;—That the velocity of motion of the north end of a magnet freely suspended in the direction of the magnetic force is a maximum when the sun makes its superior transit of the magnetic meridian (between 10" and 11” 4.m.), and a minimum when it makes its inferior transit of the same meridian (between 10 and 11" p.m.). This result is the more curious that the epoch of the minimum velocity of the diurnal motion is an epoch of maximum disturbance, and, in as far as the declination is con- cerned, the epoch of maximum velocity of the diurnal motion is also an epoch of minimum disturbance. 160. When we compare the results for the irregular disturbance, with reference to the separate elements of magnetic declination and magnetic dip (see horizontal component), with the velocities of motion as deduced from these figures, we find, that when the diurnal motion is most rapid the departures from the direction of that motion are least, and when the diurnal motion is slowest the irregular departures from the hourly mean position are greatest. 161. It is scarcely possible to connect the previous facts of area, perimeter, or velocity of motion with the laws of variation of temperature. In the mean for the whole year, the temperature changes most rapidly between 8" and 9h a.m.; but it changes with nearly equal rapidity between 5" and 6" p.m. There is no corresponding fact in the previous numbers. When we compare the variations of temperature with the variations of position for the suspended magnet in the summer months, we find the difference between the two classes of facts even more marked: in summer, the temperature changes most rapidly about 7" a.m. and 7" p.m., the change for May, June, and July, from 64-8" a.m. being +3°80, and from 62-8" p.m, being —3°-54; for the same months the mean angular motion of the needle from 62—8" a.m. =1'-00, from 95-11" a.m. =2’12, and from 6h_8h p.m. =0'-74. There is a diminution in the velocity of the motion between 1 and 2" p.m. ; there is also a slight diminution at the turning point, 6"—7" p.m. and between 2" and 3" a.m. These diminutions appear to be connected with the fact, that they occur at turning points in the figures. 162. It may be remarked that the line representing the astronomical meridian, and passing through the centre of gravity of the figures for the months during which the sun is north of the equator, also passes through the position of greatest velocity, and nearly through that of least velocity, of the diurnal motion. 163. General Form and Turning Points of the Diurnal Motions.—The general forms of the diurnal motion vary between rude ellipses and circles. In the winter months, the principal portion, or loop of the figures, is elliptical with the major axis horizontal ; near the equinoxes the figure becomes somewhat circular, and in the midsummer months it again becomes rudely elliptical, with the major axis inclined about 20° or 30° west of the magnetic meridian. In the usual investigations of the conventional element of declination, it has been re- marked that the turning from the farthest westerly position occurs near the time of maximum temperature ; a coimcidence which has been supposed to indicate a real connection, though there is no similar coimcidence between the epoch of minimum temperature and the eastern turning point. If, however, we examine the figures indi- cating the diurnal motions of a needle in its true position, such as those for the months of April, August, Oc- tober, &c., we might find it difficult to say, where is a turning point and where not; and it is difficult to see why the turning points at the extremities of the horizontal diameters of these rude circles, or at the extremities of a horizontal line, in the ruder ellipses, should be chosen, in preference to the turning points at the extremi- ties of other lines drawn in the figures, as tests for a theory; unless, indeed, it be explained by the accident that a horizontal suspension of a magnetic needle is a convenient one for observing a certain portion of the motion of a magnet, which, independently of gravity, would rest in the direction of the magnetic force. 164. It may be noticed, chiefly with reference to the months from March to October, that a line passing through the positions of noon and midnight also passes through, or nearly through, the mean position, or the centre of gravity, each hour having equal weight : also a line passing through the positions about four hours before and four hours after noon, passes nearly through the centre of gravity of the figures ; the former of these lines hes nearly in the direction of the minor axis, the latter nearly in that of the major axis of the rude ellipses for the midsummer months. The horizontal line passing through the centre of gravity, also passes nearly through the positions of 14 a.m. and 1” p.m., which, therefore, are the epochs of mean dip. (See also No. 162.) 165. Angular Distances between the Hi ourly Positions from the Mean of all, and from the Undisturbed Days. —It has been already stated, in considering the efect of disturbance on the hourly mean values of the magnetic elements, that it is assumed that the mean of all the hourly values is unaffected, which, in the present case, is equivalent to assuming, as has been done in Plate VIII., that the centre of gravity of the disturbed and un- disturbed figures is the same; this must be very nearly true, as regards its position in declination (No. 38), but it is probable that there is some error with reference to its position in dip: it will be seen from No. 123, that this error in the figures for May—June and July—August is very small; it will also be seen from No. 123, that the dotted figures for the other months should be raised somewhat in the page, since the centre of gravity of the dotted figure has a less dip than that of the continuous figure ; the effect of this elevation would be chiefly to diminish the distance between the points about 4" and 5” p.m, on the figures for March and April : Ixxiv GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. these remarks may be kept in view, in considering the numbers in the following Table, which are obtained from Plate VIII. TABLE 68.—Angular Distances between the Disturbed and Undisturbed Positions for each Hour in the motion of a freely-suspended Dipping-Needle, as obtained from Plate VIII. Mak. Dec Sept. Sept March Mean Jan March. May. July. Ook 5 to From Mean Time. Feb. April. June. Aug. Noy. Feb. Aug. Mean of first 5 Curve. Columns. bh. 5; 12 0-36 0-20 0-34 0-28 0-36 0:35 0-25 0:32 0-32 13 26 32 26 24 +28 28 oil 26 27 14 28 46 20 +18 14 18 28 24 24 15 09 16 16 -06 +12 08 12 08 12 16 06 04 18 -08 -12 09 09 04 09 17 15 08 08 +24 “14 13 14 08 14 18 2 20 08 32 +34 25 18 22 24 19 20 24 14 32 -40 29 22 26 27 20 18 30 30 -46 -42 29 34 28 a3 21 22 36 28 -30 -40 30 32 32 31 22 24 28 26 -20 +26 28 22 23a 25 23 24 30 16 36 -26 24 18 24 26 0 28 28 12 14 -30 26 18 22 23 1 35 -24 28 16 +24 28 24 28 26 2 36 -36 40 16 +38 34 30 34 34 &} 29 +32 26 24 -36 30 28 28 30 4 28 44 46 44 -16 40 44 32 33 5 12 +30 34 50 +12 04 35 18 26 6 15 -36 30 42 -32 19 235 eet 30 7 18 42 30 26 38 27 22 24 30 8 43 +36 16 24 -58 50 24 38 38 9 38 38 24 44 -44 38 34 38 38 10 39 38 30 36 +52 45 34 40 40 11 42 +26 38 22 -50 45 32 | 38 ay7/ 166. The following are the conclusions from Table 68 :— 1st, In the two figures for the months from September to February, the effect of disturbance in displacing the needle is a minimum about 4° a.m. and 4" p.m., the values for these hours being nearly equal, or near the hours when the sun is on the magnetic prime vertical. The maximum effect of disturbance occurs in both about 10" p.m., when the sun is on the magnetic meridian, a secondary maximum occurring in the figure December to February about 13" p.m., and in the figure September to November about 8? a.m. 2d, In the figure for March—April, the minimum occurs about 4? a.m., and the maximum probably about 8>—10" p.m., the value, however, varying little for the 18 hours from 8» a.m. till 2 a.m. ; 3d, The mean of the two results for the figures May—June and July—August is to some extent the reverse of the result for December to February. The effect of disturbance is a minimum about 4" a.m., and about noon ; it is a maximum about 8" a.m. and 42 p.m. It would appear, therefore, that the diurnal law of the effect of disturbance varies with season as well as the law of the amount of disturbance (see Nos. 45,77, 110): a minimum is also shewn about 8? p.m. 4th, Inall months of the year the effect of disturbance is a minimum about 4 a.m. In the winter months a minimum occurs at 4! p.m., the maximum occurs at the same hour in the summer months. 5th, Inthe mean figure for the year, minima occur at 4" a.m. and about 53" p.at., the maximum occurs about 10” p.m., and a maximum oceurs between 8" a.m. and 4" p.m. If, making allowance for the effect of dis- turbance on the position of the centre of gravity with reference to dip (No. 121), we suppose the centre of gravity of the dotted figure for the year (Plate VIII.) raised 015 on the line of mean declination, or that of the continuous figures lowered as much, we find the maximum effect of disturbance to occur about 10" pP.at. and 10" a.m., and the minimum effect about 4" a.m. and 5" p.w. This result was obtained for the magnetie de- clination in 1844. See the Volume for that year, p. 345. Tue AURORA BOREALIS. Ixxv 167. Motions with reference to the Moon’s Hour-Angle.—These, as obtained from the means of all the luna- tions in the years 1844 and 1845, and as deduced from winter lunations for 1845 only, are shewn in The resulting figures, especially that for the winter lunations of 1845, bear some resemblance to the diurnal motion for the month of December. _ Plate VII. Tur AURORA BOREALIS. 168. The results for the aurora borealis are placed between the magnetical and meteorological discussions, because the appearances of this meteor are distinctly connected with magnetic disturbances ; the frequency of the one and the magnitude of the other, it will be seen, are governed by the same laws. 169. The following Table contains a list of all the aurore seen at Makerstoun, between January 1843 and A very careful outlook for aurore was kept throughout the whole period, but especially during the first five years; an outlook warned by magnetic disturbance in circumstances unfavourable to the visibility June 1849. of the meteor, and assisted by a practical acquaintance with the faintest auroral indications. In several cases, the auroral appearances were very faint; these are entered in the Table as ‘‘ Traces,” and, in others, there was doubt whether the appearance was truly auroral ; these are indicated by “ Trace ?” with the exception of the years 1844 and 1845, aurore were seldom looked for after midnight. Date, Gottingen Mean Time. 11—12 TABLE 69.—List of Aurore Boreales seen at Makerstoun in the years 1843-9. Character of Magnetic Disturbance. Sky Clouded. Species of Clouds. General Remarks. Slight Moderate Moderate Moderate Considerable Moderate Considerable Considerable Moderate Moderate Seud Cum.-seud Scud Cirro-str. Cirrous Seud Cirrous Loose cum. Slight Moderate Slight Slight Slight Moderate Moderate Slight Various Cir.-strati Sc. ; cir.-str. Scud Scud Seud Cirri Loose scud Cirri Cirri Seud; cir. Cir.-str. Se. ; cirri Cirri Cirri Cir.-str. Cir.-str. Cirri Cirri Moderate 2Moderate Moderate Slight Slight Moderate Moderate Moderate Slight Moderate Moderate Slight Considerable Moderate MAG. AND MET. oBs. 1845 anv 1846. Traces. (Seen at Christiania.) Traces. (Seen at Christiania and in United States.) Seen through clouds. Arch 10° altitude, Distinct. Segment of circle 15° alt. 103", equatorial beam. Bright arches and streamers. 144; arch 10° broad, 15° altitude. Corruscations. Bright. 145 35™; 12° altitude. 115; band 10° altitude ; seen through clouds. Traces. (Seen at Christiania.) Auroral arch 15° altitude. Streamers. Traces through clouds. 92 50™; arch 8° altitude. Traces, Distinct. [places. Traces. 125; magnets slightly disturbed at other Distinct. Traces; through clouds, (Appearances at Parma.) Traces. Traces. Traces. Faint. Traces. (Suspected at New Haven, Connecticut.) Traces. Trace. Rather bright. Rather bright. Faint. Bright. Arches and streamers. Streamers, arch and band. Traces. Faint streamers and homogeneous light. Faint. (Bright moonlight.) Arch and streamers. Tt should be noted that, Page of Refer- ence. lxxvl GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. Date, Gottingen Mean Time. Moon’s| Sky Species Age, |Clouded. of Clouds. |May 21 12 4 2-0 | Cirri 22 11 5 0-2 | Haze fAug. 2 14 18 0-5 | Cirri 9 14 25 3-0 | Scud | Oct. 2 8—10) 20 1:0 | Cirri 7'11—12)- 25 0-5 | Cirri 20 14—18 10 0-5 | Cir.-str. i Nov.11 6—14 1 0-5 | Cir.-str. 12 14 2 | 10-0 | Scud: 13 10 3 8:0 | Scud 16 10—11 6 7.0 | Cirri 18 9 8 10-0 | Seud 24 13 14 1:0 | Cirri iDec. 4 8 24 0-2 | Cir.-str. 29 6—14| 20 Cirri lJan. 0.15—16| 22 | 5-0 | Cir.-cum. H 9 7—14 1 0-5 | Cirri 19 12 11 9-0 | Cir.-cum. 20 11 12 9.5 | Cir.-cum. 21 8 13 9-5 | Scud 23 15 15 10-0 | Cir.-str. 24 13 16 0-5 | Cirri 26 13—15)} 18 4-0 | Cirri 28 8—12)| 20 6-0 | Cir.-str. 99 7F—9| 21 1:5 | Cir.-str. | 30 8—10|} 22 0-5 | Haze iFeb. 1 12—13| 24 0-8 | Cirri 5 8—13) 28 9:0 | Cirrous 7 14—15 1 2-5 | Cirrous 26 15 20 3-0 | Cir.-cum. 298 12—14| 22 4-5 | Cirri }Mar. 9 16 1 10-0 | Scud 14 11 6 4:0 | Seud 18 10 10 2-0 | Cir.-cum. 19 10—13 11 0-5 | Cir.-str. 90 14—15| 12 0-5 | Cirri 23 13—14| 15 5-0 | Cirri 24 15 16 4-0 | Cirri 25 9 17 9-8 | Cir.-str. 26 11—14} 18 4:0 | Seud 28 10—11| 20 0-8 | Cir.-str. 29 11—12 21 0-8 | Cirri Apr. 13 11—16 7 7:0 | Cir.-str. WD 11 9 8:0 | Cir.-cum. 19 11 13 4-5 | Seud 30 11—14| 24 7-0 | Seud May 11 13—14 5 1-5 | Cir.-str. Aug. 29 10—13 26 0-3 | Cir.-str. 30 12 27 1-0 | Cirri Sept. 2 10—12 1 0-2 | Cir.-str. 25 16 24. 0-8 | Cir.-cum. 27 9—10} 25 5-0 | Seud Character of Magnetic Disturbance. Slight Moderate Moderate Moderate Moderate Slight Slight Considerable Moderate Moderate Slight Large Moderate Moderate Large Slight Large Moderate Slight Moderate Moderate Moderate Moderate Moderate Moderate Moderate Slight Moderate Slight Moderate Moderate Moderate Moderate Moderate Slight Slight Moderate Moderate Considerable Moderate Moderate Moderate Slight Considerable Slight Moderate Moderate Slight Moderate Slight Moderate Moderate Moderate TABLE 69.—continued. General Remarks. Traces. Trace. (Seen at New Haven.) Faint. [tucket, Mas.) Traces. (Seen at Whitehaven, and at Nan- Belt of light 5° altitude. Faint. Faint. Bright. Arches and streamers. Distinct. Arch and streamers. Traces through clouds. Trace. (Seen at Christiania.) Arch 5°—8° altitude. Patches Faint. and streamers. Portion of an arch 10° altitude. Faint. Brilliant. Arches, patches, and streamers. Faint. Bright. Arches, brushes, and streamers. Traces. Traces. (Seen in Orkney.) Traces. Seen through a break in the clouds. Traces. Auroral appearances between the clouds. Distinct. Faint. Traces. Milky aurora. Arch and streamers. Milky aurora. Arch 8° altitude, and streamers. Trace 2 Faint ; milky aurora. Seen through clouds. Traces ? Faint. Faint. Faint. Faint. Traces. Trace ? Traces. Faint. Faint. Brilliant. Arches and streamers. Trace ? Trace. Faint. Faint. Distinct. Belts and streamers Faint. Seen through clouds. Distinet. Streamers. Faint. Faint. 9" arch 7° altitude. 105 ; streamers. j THE AURORA BOREALIS. Ixxvil if | TABLE 69.—continued. poate, Moon’s} Sky Species CEES Page Mean Time, | AB® [Clouded of Clouds. | pst bance, Hana aM | reste 1845. | 4d. h.—h. a. (1845.) Oct. 1 16 0 6-0 | Scud Slight Trace. (Seen at Christiania.) 238 20 13 19 0-0 Moderate Faint. Patches and streamers. 124 21 15—17) 20 2-0 | Cirrous Moderate Faint. 245 31 11—12 0 5:0 | Cirrous ‘Slight Traces. (Seen at Christiania.) 249 Nov. 4 11—12 5 0-0 Slight Faint. Diffuse light, with streamers. 124 Bo 5 0-5 | Cirri Moderate Arch 12° altitude. 124 Vie e—l1\- 17 0-5 | Cirri Moderate Bright. Arches, streamers, and brushes. 124 Dec. 3 6—18 4 0:0 Very large | Brilliant. Arches, streamers, and brushes. 125, 261 13 10 14 0-0 Moderate Trace. 265 1846. (1846.) Feb. 25 9—12 0 0-5 | Se.; cir.str. | Moderate Arch and short streamers. 342 126 10—11 1 8-5 | Seud Moderate Diffuse light and faint streamers. 342 Mar.16 9—12| 19 9-8 | Scud Considerable | Faint light, arch, and streamers. 342 | Apr. 6 11—13) 10 Cir.-str. Moderate Faint. 342 16 10—11}| 20 1-0 | Scud Considerable | Faint. 342 Aug.24 11—12 33 0-0 Moderate Diffuse light, with faint streamers. 342 27 10—12 6 8-0 | Scud Considerable | Distinct. Patches and streamers. 342 Sept.10 9—10| 19 5-0 | Cirri Moderate Faint. Arch 7° altitude. 342 ie O==11' |) 20 3-0 | Cir.-str. Considerable | Faint. Beam. [bank 5° alt. | 342 21 13—16 1 8-0 | Scud Considerable | Distinct. Incessant pulsations of patches. 155; | 343 22 10 2 8-0 | Cir.-str. Very large | Evidently bright, but obscured by clouds. 395 Oct. 8 8—9| 18 6-0 | Cir,-str. Considerable | Aurora. Faint streamers. 343 o 19 2-5 | Se.; cir.-str. | Moderate Bright streamers. 343 19 10 29 3:0 | Se.; cir.-str. | Slight Faint. 399 22 10 2 9-8 | Cir.-str. Moderate Traces; through clouds. 343 Nov.17 7— 8| 28 4:0 | Sc.; cir.-str.| Large Bright. Arches and streamers. 343 Dec. 9 9—10) 21 0-5 Moderate Arch. 343 1847. N.B.—See additional Notes after Table 69. | Jan. 30 9 13 Moderate Faint. [like clouds from NW. Feb. 6 8—10| 20 Cirrous Slight Faint light. Arch and streamers; cirrous-fan- 4 Mar.19 8—12 3 Cirrous Very large |(Bright. Corona borealis. 8" 50™; arch about . 10° alt. from NNW. 9? 20™; arch about 20° alt. from SSE. | Apr. 3 10—11) 17 Cir.-cum. Considerable | Pulsations seen to 20° altitude above clouds. Aug.22 14 12 Slight Faint. Varying patches. i | Sept.26 7—I11| 17 Beautiful. Streamers, arches, brushes, waves, &c. | 299 8—12}| 20 Cir.-str. Large Pulsating patches, diffuse light, arches, stream- Oct. 8 8 29 Sc. ; cir.-str. Traces. [ers, &c. 146 8 7 0-0 Moderate Faint, with streamers. | 19 11 10 Scud Slight Low band. Streamers close to horizon. 24 14 15 Cir.-str. Excessive 115 7™ ; Splendid corona, &c. 29 7—11] 20 Scud Moderate Faint. 84; arch 8° alt. 115; streamers on horizon. Nov. 1 7 23 Seud Slight Traces. | Woo | 14 Seud Large Fine red-coloured patches and streamers. 10412™; oF \ corona borealis centre71° alt.,azimuth 8. 25° E. 25 10 17 Sc.; cir.-str. | Moderate Faint. 26 10 18 Cir.-str. Slight Faint. 27 10—11| 19 Stratus Moderate Distinct. Dec. 20 8 13 Seud Excessive Splendid crimson aurora, with corona borealis, &c. | 1848. x Feb. 20 10—12| 15 Brilliant. Coloured ; streamers and corona bor. 21: 9—10} 16 Id. Much concealed by clouds. | 710! 17 85 50™; arch passing through zenith. Id. { 8 55™; lower edge of arch 42° above SSE. Ixxvili Date, Gottingen Mean Time. | 1848. H d. h—h Mar.17 9—10 19 8—13 21 12—13 24 10 Apr. 17 10 29 9—13 May 10 11 18 13 Sept. 5 12 Oct.18 7—11 19 20 21 22 12 24 10 26 11 Nov.17 7—13 18 9—11 21 7—10 22 8—lli1 30 10 Dec. 17 7—13 21 10 1849. Jan. 5 12—13 14 6—11 15 8—11 16 7 25 8—ll 26 8—l11 31 10 Feb. 11 10 13 11 18 8—lil 19 9—12 20 9—10 21 9 22 7—12 24 10 26 10 28 10 Mar.18 10—11 19 11—12 Apr. 16 8—11 17 11 GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. Sk TABLE 69.—continued. Species Nf . |Clouded.} of Clouds. Character of Magnetic General Remarks. Disturbance. After this He Traces; through clouds. Bright arch of brushes. Bright and rapidly pulsating. Faint. | Coloured, but sky overcast with growing clouds. | Faint. 115 10™; streamers. Faint. Streamers. Bright. Streamers to 80° alt.; coloured red. Faint. Lightning. {and thunder. Coloured. 103; corona borealis. 115; lightning Faint. Streamers. Traces, Traces. Aurora, with streamers. [the 23d 2) Traces. Overcast. (This may have been on | Faint. | Magnificent, whole sky crimsoned. | 104; arch about 10° altitude. Bright. 85 10™; large wing-like patches about ‘ the anti-dip. Bright, but sky overcast with clouds. Traces. Brilliant. 84 40™; corona borealis. 11% 40™; ' beautiful wings about its centre. Faint. Low on north horizon. Aurora, with streamers. [arch 15° alt. 6" 10™; streamers. 9° 40™; arch 4° alt. 105 40™; Diffuse light. Traces ; through clouds. Faint diffuse light. Very faint. Trace. Very faint. Very faint. [to N. by E. 9» 40™; rather bright, with pink or red patches 8 40™; bank to N. 95 54™-58™; magnificent bow. 10° 0™; bank, or red streamers. Diffuse light. Very faint. 7+ 20™; finely coloured to N. 11°48™; corona bor. Very faint, with low arch. Faint. Trace. [and streamer. | 10° 25™; fine arch 73° alt. 10°32"; low light | Faint arch to N. (Streamers, and pulsating wings about the centre \ of the corona borealis, Faint. time little watch was kept for Aurore. Faint. Faint. | Faint, with short streamers. | | Distinct traces on N. horizon. Faint streamers. ence, . THe AvurorA BOREALIS. lxxix 170. The detailed notes on the aurore seen till January 1847, will be found in the volumes referred to in the last column of the previous Table: in order to render the series more complete, the following additional notes for the year 1847-9 are given. Gottingen mean time has been employed, as in the former volumes, in order that the notes might be comparable with the magnetic observations. Gott. M. T. WS4(e 0", a vivid flash of lightning followed in about two seconds by a peal of thunder ; heavy shower of hail or snow. The magnets considerably disturbed about 7°. Aurore were seen at Inveresk by Mr Milne’s gardener on the following days, when none were ob- served at Makerstoun, viz., April 24; July 1, 2, 23; and August 8, 1848, MAG. AND MET. OBS. 1845 anv 1846. u Ixxx GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. Gott. M. 'T. TBO N cdeoeah: Hebe slo 8 40™, Homogeneous auroral bank to N. with slight appearance of an arch. 9 54™_58™, Magnificent bow of aurora passing between Castor and Pollux, as in Fig. 1; shortly afterwards a series of waves seemed to move along the lower edge of the bow from east to west, and in a di- rection opposite to the very violent wind then blowing from west; the appearance of the waves is shewn in Fig. 2. 10 10™. The source of the waves was observed as in Fig. 3; the bow was seen to be at the base of a series of beams, which converged to the anti-dip ; the beams were but faintly visible, but they were obsery- ed to rotate about the point c, the centre of the corona, the beam a, appearing to occupy successive positions, till it arrived at the position b; in this rotation the wave-like motion observed in Fig. 2, was produced. The sky was quite clear, and the wind blowing very violently. It is not a little curious that on the following evening, Feb. 20th, Professor Forbes observed a similar arch in almost the same position. He has obliged me with the following note of his observation :— “ Edinburgh, 20th February 1849.—At 10> 10™, p.m. [Greenwich mean time], my attention was called to a splendid auroral arch; the brightest I ever saw. Sky clear and calm blue, diffuse light in N. At 10" 11™. Centre of band over northermost of two bright stars in Gemini (Castor and Pol- lux). Motion at first a little northwards, but returned to its former position. Undulations of bright- ness from EH. to W. passed along the zone. Began to break up from the E. end about 105 18™: figure became.irregular, and, on the whole, to the S. of its first position, 10" 22™. Only streaks in the west remaining.” March 18 10 25™. The arch passed between the stars, 38 and 40 of the Lynx, which were nearly on the meridian ; at 10" 32™, the arch passed over the two stars, A and « Urs Majoris. Diurnal Variation of Visible Frequency of the Aurora Borealis —When we note from the preceding Table the hours at which aurore were seen at Makerstoun, we obtain the numbers in the following Table. TABLE 70.—Number of times that the Aurora Borealis was seen at Different Hours in the Years 1843-9, as deduced from Table 69. Mak. | | | Nov. | Feb. Aug. Mean || Jan. Feb. | March.| April. | May. | Aug. | Sept. Oct Nov. | Dec. || Dec. | March.| Sept. || Year. Time. | | | | | Jan. | April. | Oct. rtd is =| | | | fe | | | | 5pm. ||. 1 0 0 Wo kG 0 Oral uri Tidgs 5 o | 0 5 Guides adits 12 SP 1) 0 0 0 1 2 Sh zoe | Sa eee ae 2 3 19 fl 10 Mes Ll eo HIRO 2 8 7 oil) Gomi es 12 | 10 || 45 8 9 12 9 3 0 0 5 6 9 4 22 24 11 57 9 10 LZ ied 2 6 0 rt 10 12 16 7 || 33 Soles 91 10 | § LOW as 12 eas 2 7 8 9 3 || .20 35s ale 75 11 4 9 10 Cala? 3 5 3 4 ial ele 26 | All oii 12. d 6 8 7 2 1 2 I 3 3/10.) 21.) 45 lee 1 A.M 2 3 5 5 l 3 2 2 2 25 sila 13. [> lle 2 3 2 3 2 0 0 2 Dsl hb Oras peed cin mi i 4 15 3 1 Ob ee 2 0 0 2 Sicilians)? witha tl eat ae 5 ll | 0 0 0 One 20 0 0 I 1 fatal toe Oa 3 5 | 0 0 (0) ON Orel AW 0 l 0 | DF | 1 | 2 FREQUENCY OF THE AURORA BOREALIS. Ixxx1 171. Itis probable that the numbers for midnight, and the hours thereafter, are too small, for the reason given, No. 169. The greatest number of aurora were seen at 9" p.m. ; this result is independent of the effect of twi- light, since 9" p.m. is also the hour of maximum frequency for the winter months. This hour is nearly the hour of maximum disturbance for the magnetic declination and dip; as, however, the maximum disturbance of the total magnetic force and a maximum of the magnetic dip appear to occur about 5” p.m., this also may be an epoch of maximum frequency or intensity, though this can only be determined in higher latitudes. It should also be remarked, that, since the epoch of maximum disturbance varies with season, so, therefore, it is probable will that of frequency of the aurora; some traces of this may be deduced from the previous table. In the winter quarter, November—January, four-fifths of the times at which aurore were seen were for the hours before 10» p.m., whereas in the spring quarter there were only three-fifths seen before 10h p.m. (See No. 172). TABLE 71.—Numbers of Aurore Boreales seen at Makerstoun in each Month of the Years 1843-49. Years. || Jan. Feb. |March.| April. | May. | June. | July. | Aug. | Sept. | Oct. Nov. Dee Sum.” 1843 1 1 4 2 | id) Only 30 0 3 3 3 3 20 1844 2 3 5 3 3 Oe 2 0 4 6 2 30 1845 || 11 6 Tie ee 1 0 0 2 3 4 3 2 47 1846 0 2 1 2 0 On |40 2 4 4 1 1 17 1847 I 1 1 1 0 0 Olay) sail 2 5 5 1 18 1848 0 3 4 2 2 O/iiife 20 0 1 7 5 2 26 1849 7 10 2 2 0 One. 20 * * 3 Dall per Reni hy: 26 ley er & ila me | 1G NG OO tiara ice theo) oon li) al 184 172. Annual Variation of Frequency of the Aurora Borealis.—The first line following contains the numbers of aurore observed in each month during the six complete years 1843-8, and the second line gives the numbers ___ of hours at which the aurorz were seen. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 15 16 26 14 6 0 0 Gi 13 27 23 it 50 62 65 43 8 0 0 10 32 44 58 36 The greatest number of aurorz was observed in March for the first six months, and in October for the last six months of the year: none were observed in June and July. When the six months of 1849 are in- eluded, the number for February is 26, and for March, 28. The law of visible frequency of the aurora 1s the same as that deduced already for magnetic disturbance, namely, maxima near the equinoxes, and minima near the solstices, the minimum at the summer solstice being the principal.* As, however, the shortness of night during the summer months must diminish the number of visible aurore, it is by no means certain from these numbers that a minimum occurs at the summer solstice; the fact of the minimum at the winter solstice is involved in no such difficulty. If we could assume that the aurore had the same diurnal law of frequency at all seasons of the year, the existence of the summer minimum could be satisfactorily determined, by comparing the numbers of times which aurore were seen at the five hours, 10h p.m—2" a.m., during * It has been stated in the volume for 1844, p- 401, that this result was long ago obtained by Mairan ; this statement, made chiefly on the authority of Kemtz and Hansteen, is not quite accurate. It is true that Mairan’s numbers give a rough indica- tion of the law, as will be seen below; but when it is remembered that his table includes all the observations (229) of which he could find a record for upwards of 1000 years, it will be evident, that the conclusion that a greater number of aurore occurred at both equinoxes than at the winter solstice would have been hasty ; this conclusion, however, is not made by Mairan, and, though he has combined the numbers of aurore in a great variety of ways, he has made no combination exhibiting this fact. It did not enter into the necessities of his theory (that aurore are the product of the solar atmosphere) to shew that a greater number of aurore hap- pened in the northern hemisphere, at the vernal equinox than at the winter solstice; he shews, indeed, that the number for one equi- nox is, and, in accordance with his theory, ought to be, greater than for the other. Some other philosopher has the merit of first pointing out this fact. The following are the numbers of aurore by Mairan (Traité Physique et Historique de 1’Aurore Boreale, par M. de Mairan, ad Ixxxll GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. which (even in the months of August and May) there is little twilight to extinguish aurore. The numbers are as follow, for these five hours in each month of the years 1843-8 :— Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Noy. Dec. 15 24 38 ol 8 0 0 9 14 16 18 12 From these it is evident that the numbers in May and August are certainly less than for April and Sep- tember; but it has been already mentioned as probable that the diurnal law of frequency varies with season, of which, indeed, a proof is to be found in the great excess of the numbers above for the spring months, com- pared with those for the autum1 months, shewing the later epoch of the maximum frequency in the former. An examination of Table 18, however, will shew, that, though the maximum disturbance occurs after midnight, in the months of May, June, and July, yet in August and the two following months it occurs about 10" p.m, so that there can be no doubt of the less number for August than for September and October, if there should be a doubt in the case of May compared with April. The difference, however, even in the latter case is too great to be explained by any slight shift of the epoch of maximum frequency in the two months. Upon the whole, it appears certain that a minimum of actual as well as of visible frequency occurs in summer; a result quite in accordance with that for the amount of magnetic disturbance, which accordance is sufficiently close to. permit us to complete it, by assuming that the number of aurore is a principal minimum in summer. 173. Variation of Frequency of the Aurora Borealis with the Moon’s Age.—This investigation is evidently beset with considerable difficulty, since the moonlight existing nearly extinguishes the appearances of all the fainter class of aurore, and it renders the faintest wholly mvisible; the careful watch, however, which was kept for auroral appearances at Makerstoun, probably renders Table 69 better fitted for such a question than any previous series of observations.* 174. Combining the numbers of aurore observed at each day of the moon’s age into six groups of 5 days (the first group, 4} days), we find the average number of aurore for one day of the moon’s age in each group as follows, from the 63 years’ observations :— Moon’s Age. 284—2d 34—74 84—]2¢ 134—174 184—224 2349274 Number. "5-8 5:2 3:6 5-0 10-2 6-6 Did aurore occur indifferently at all ages of the moon, we should expect to sce the greatest number at conjunction, and the least number at opposition; this however is not the case, the greatest number was seen about two days before the end of the third quarter, and the least number about two days after the first quarter, or the visible maxi- mum and minimum occurred at times equidistant from the epoch of opposition. The frequency of aurora, ° therefore, is a function of the moon’s age. In order to determine the actual law, we may consider the probable effect of moonlight in obliterating the auroral appearances ; remarking, first, that 9> P.at, is the epoch of maximum frequency for the aurora, and that upwards of five-sixths are seen before midnight. When the moon is about three days old, in the months from September to March, it begins to set sufficiently late, and to have sufli- cient light to render the earlier of the faint aurore invisible ; about the end of the first quarter, it does not set till midnight, and thus shines throughout the period of the occurrence of five-sixths of the aurore ; afterwards it increases in brightness, and the maximum effect in extinguishing faint aurore is evidently attained at opposition, when the moon begins to rise late enough to allow the earlier aurore to be visible; towards the end of the 1733, p. 199); by Kaemtz (Complete Course of Meteorology, translation by Walker, p. 458); and by Hansteen (Mem. de l’Acad. Roy. de Belgique, t. xx., p. 117). Jan, Feb. March, April. May. June. July. Aug. Sept. Oct. Noy. Dee. Sum. Mairan, . 21 27 22 12 1 5 7 9 34 50 26 15 229 Kemtz, 229 307 440 312 184 65 87 217 405 497 285 295 3203 Hansteen, 29 31 47 34 2 0 0 17 35 33 34 23 285 J. A. Broun, 22 26 28 16 6 0 0 7 16 29 23 ll 184 Sum of last three, 280 364 515 362 192 65 87 241 456 559 342 259 3722 Mairan’s numbers are probably included by Kexmtz; a few of the aurora, included in M. Hansteen’s list, are identical with those in my own. * Tt should be remarked, that the latitude of Makerstoun, or perhaps even a lower latitude, is better fitted for this investiga- tion, than much higher latitudes; at least this is the case as long as only frequency of visibility can be considered. The French Commission du Nord, during their stay in Lapland, found aurora existing, or probably existing, almost every night. In such places variation of frequency there is none, and variation of intensity alone remains for investigation. It is obvious, that till some better mode of measuring this intensity can be devised for these high latitudes, we are forced to perform this operation in a rude manner, by moving to lower latitudes, where the fainter aurore become invisible, and where, therefore, frequency is a test of intensity be yond a certain limit, SR —— ee ec oe = ore -w A rete SS SS — ameter, THe AvrorA BOREALIS. Ixxxill third quarter, when the moon does not rise till midnight, it is also evident that the number of faint aurore rendered invisible must be very small. From the beginning of the fourth quarter, therefore, till conjunction, the numbers seen will obey nearly the true law of frequency; and as the visible maximum occurred before the end of the third quarter, the true maximum must have occurred even nearer to opposition. On the whole, it appears very certain, that the hypothesis of an actual maximum of frequency at opposition and minimum at conjunction, is satisfied by the previous numbers of aurorz, seen under the conditions of the varying duration of moonlight for the hours of maximum frequency. This hypothesis is in unison with the law of magnetic disturbance, which is a maximum at opposition, and a minimum at conjunction, NOTE ON THE THEORY OF THE AURORA. 175. Although temptations to frame hypotheses have been avoided hitherto, I cannot refrain from repeating here, the opinion, that the phenomena of the aurora borealis are chiefly optical. After watching the various phases of the aurora for some years, the hypothesis of self-luminous beams and arches appeared to me unsatis- factory, and the strongest argument in its favour, that obtained from the computed height of the auroral arches, seemed of a very doubtful character. I was quite prepared, therefore, to adopt the idea, first I believe pro- posed by M. Morlet to the French Academy, in May 1847, that the auroral arch is an optical phenomenon of position. M. Morlet has pointed out that the arch appears generally as a segment of a circle, whereas, in these latitudes, it ought invariably to appear as the segment of an ellipse, if the hypothesis be true, of a real lumi- nous ring, with its centre on the continuation of the magnetic pole. He has also, among many other very obvious, objections to that hypothesis, shewn that the summit of the arch is generally in the magnetic meridian of the place, the plane of which rarely passes through the magnetic pole, and seldom passes through the same point, for three different places. I have, however, felt even more persuaded, that the aurora is, partly at least, an optical phenomenon, from a consideration of that phase of the aurora constituting the corona borealis, a persuasion that I stated, in the Literary Gazette of the time, in giving an account of the beautiful corona of _ October 24, 1847. Mairan and, more lately, Dalton, have explained this phase of the aurora by a hypothesis of polar beams, long fiery rods of solar atmosphere, according to the one, of red-hot ferruginous particles accord- ing to the other, seen in perspective, as they le in the direction of the magnetic force. A little acquaintance with the phenomenon—the rushing and tilting of the beams against each other, one beam occasionally rising from the horizon, passing through the centre of the crown and beyond it—would shew the improbability of this hypothesis. I am persuaded, that the phenomenon of the corona borealis is produced in a narrow horizontal stratum of the earth’s atmosphere. Thanks to the discoveries of Dr Faraday, we do not now require a ferruginous sea, in order to have polarized particles ; the watery crystals that inhabit the upper regions of the atmosphere can themselves assume a polar state, determined by the passage of electric currents ; and we have only to com- plete this fact by a hypothesis of luminous electric discharges seen refracted by these crystals, the position of visibility of the refracted rays depending on the angles of the crystals, and the deflections from the direction of magnetic force, which they suffer by the electric currents. Such a hypothesis, which occurs at once when an optical phenomenon has to be accounted for, would explain these remarkable auroral clouds, so often seen in connection with the aurora itself; it would also serve to explain the appearance of the arch at certain alti- tudes, lower for lower altitudes, determined by the position of the source of light, direction of the magnetic force at the place, and the effect of the electric current in deflecting the crystals. The crystals successively deflected by electric currents, would also exhibit the rushing pencils or beams. It need scarcely be remarked that, dif- - ferently formed crystals might give rise to different phases of the phenomenon, while reflection might be tom- bined with refraction in certain cases, especially in the case of arches seen south of the anti-dip. Such a hypo- thesis evidently assumes a source of light, independent of these optical resultants, and the pulsations seen in many aurore may be real luminosities. It is hazardous, in the present ill-arranged state of auroral observa- tion, to offer so rude a sketch of a new hypothesis, although we may suffer a considerable defeat in very good company. - Since the previous note was written, I find that M. Morlet has published a theory of the auroral arch (Ann. de Ch., t. xxvii., 3me Série). The ideas above were stated by me two years ago, to different persons. MAG. AND MET. ozs. 1845 anp 1846. lxxxiv GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. METEOROLOGICAL RESULTS. TEMPERATURE OF THE AIR. TABLE 72.—Monthly Means of the Temperature of the Air at Makerstoun, for the Years 1841-9. | ; , | Mean | Monthly Month. . . . - | 1845. 40. . . . 1842-9, \Variations. January . 38. -35 | 34-71) 41-06 February . 2: . 32-96 | 42-52 March : . -36 35-39) 39-96 April : : 77, 44.33) 42-32 May : 5 : 46:37 51-15 June o7: “ ‘14 55-66) 61-20 July . . 05) 54-14) 58-65 August 08 54-60} 59-16 September . . : : 50-06) 55-69 October [3 ons 9: : 47-86 | 47-58 November Js : : (2. 41-94| 43-02 December : : 32. 37-08 32-53 Year. | 17} 45- 5-01| 44-59) 47-90 176. Mean Temperature at Makerstoun,—The mean temperature of the air in the shade, as deduced from observations in the 8 years, 1842-9, = 46°:03, with a probable error of 0°24. The year 1845 had the lowest mean temperature and the year 1846 had the highest, the former being 1°-44 less than the mean of the 8 years, and the latter being 1°-87 more. The mean temperature at Makerstoun for any future year = 46°0, with a probable error of 0°-7, Naming the three coldest months, the meteorological winter, the three hottest, summer, and the interme- diate quarters, spring and autumn, we find their mean temperatures at Makerstoun, as follows : _ Meteorological Winter, Dec., Jan., Feb., Mean Temperature = 36°97 Spring, | MarchseAtprilsaMiayar se.c..:--seeeeeere = 44°24 Summer, oJ une tuys wAul miei sce ce ee. sac = 56°25 Autumn; Sept. hOCtssmNOvesni ce cceu-cse erences = 46°-66 177. Annual Variation of Temperature——By the monthly means from the 8 years’ observations The maximum temperature occurred anu oximately July 22 The minimum temperature +. see see cee eee eee eee eee January 7 The mean temperature steseeeeeeeereereeeeees April 29 and October 14 The lowest monthly mean temperature occurred in 4 years in January, in 2 years in December, and in 2 years in February. The highest monthly mean temperature occurred in 4 years in July, in 2 years in June, and in 2 years in August. The highest monthly mean temperature occurred June 1846, = 61520 The lowest monthly mean temperature occurred December 1844, = 32°04 The range of the monthly mean temperature in 8 years therefore = 29°16 The greatest yearly range of monthly mean temperature occurred in 1846, = 28°67 The Teak C0 cee coe cee cee ee cae cee bee wee Oe Oe cee tee Bee cee cee nee eek eee 1849, = 19°59 The difference between the temperatures of the hottest and coldest months in the mean of 8 years = 20°95 BOSC EROS DSRS OEE CREM aati SOMOS crise SotixioooosuayeUssUNes 2 months — ...... odes Cid eee caus eee clota siaiininn dane eotiee Siege Sete OR Ghee MORE eR eI CC S months ..iacsscseccnes | | | eS | ANNUAL VARIATIONS FOR THE TEMPERATURE OF THE AIR. Ixxxv 178. We may employ the monthly means in the 11th column of Table 72, for the purpose of predicting the mean temperature for a coming month, the probable error of the predicted temperature for each month as deduced approximately from the Table, being as follows :*— Jan. Feb. March. April. May. June, July. Aug. Sept. Oct. Nov. Dec. 2°-0 2°9 11 1°°9 1°-9 1°-7 1°-4 1a na) Tesi ey 3°:2 Thus, at Makerstoun, there are equal chances that the mean temperature of any month of March will not be more than 1°-1 from 39°5. The months of March, October, and November, shew the least variation of monthly mean temperature ; the months of December, January, and February shew the greatest variation. TABLE 73.—Monthly Means of the Diurnal Ranges of Temperature, as deduced from the Observations of the Register Thermometers, for the Years 1843-6. | March. | April. 14-1 | 15.2 ies, | new! 14-0 20-2 14-7 14.3 | 14:0 | 17.0 179. Annual Variation of the Diurnal Range of Temperature—F rom the last line of Table 73, the mean of the diurnal ranges of temperature was least in December, and it was greatest in June and August. It appears probable, however, that when a suflicient number of years’ observations is considered, the mean of the diurnal ranges will be found to vary little from April till September. This result is analogous to that obtained for the ranges of the mean undisturbed diurnal variations of the magnetic elements. The ranges of the monthly mean diurnal variations, from the hourly observations in the two years 1844-5, are as follow :— Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. Seovme e009 30 L4s7OmeliB80F 4120-15) 122-00). 12°35 12°60 8°20 5°-05 38°-70 These quantities indicate a result quite similar to that obtained from Table 73, though, as might be expected, the ranges are considerably smaller. December has the least range, and May, June, and July have rather less ranges than April, August, and September. TABLE 74.—Mean Differences of the Daily Mean Temperature from the Monthly Mean for each Month in the Years 1843-6. Mean. 3-90 3-32 3-61 3-73 3-64 * These numbers divided by 3 will give approximately the probable errors of the monthly means in the 11th column of Table 72 as the true monthly mean temperatures at Makerstoun. Ixxxvi GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 180. Differences of the Daily Mean Temperature from the Monthly Means.—From the means of the results for the four years 1843-6 in the last line of Table 74, the differences of the daily mean temperature from the monthly mean temperature are greatest in the six months October to March, and they are least in the remain- ing six months; there are irregularities in the value of the mean difference from month to month; the mean — difference is less in December than in the immediately preceding and succeeding months, and it has nearly the same value as in June. The mean difference is greatest in January, and it is least in August. From the four years’ observations the mean temperature of a civil day differs on the average 3°°6 from the mean tempera- ture for the corresponding month. 181. The irregularity of the monthly mean temperature does not seem to be connected with that of the daily mean temperature; thus, March and October, which have the least variation of monthly mean tempera- ture, have the greatest variation of daily mean temperature, with the exception of January. 182. Diurnal Variation of Temperature.—Table 75 has been formed in the manner already described for Table 12. The approximate epochs deduced from Table 75 are given in Table 76. TABLE 75.—Diurnal Variation of the Temperature of the Air for each Astronomical Season and for the Year, deduced from the Observations of the Years 1843-6. SS SSS SS SS Mak. | Nov. Feb, May. Aug. : 5 : May. Aug. | Mean | Dec. Mar. June. Sept : June. Sept. Year Time Jan April. July Oct. 0 July. Oct. h m. ° ° ° ° ° ° 12 10 | —0-99 | —3-06 | —4-82 | —3-84 +4-72 | +5-42 | +5-84 | ae 13 10 || —0-98 | —3-32 | —5-.22 | —4.24 +5-30 | +5-88 | +6-42 || +5-16 14 10 || —1-10 | —3-56 | —5-61 | —4-58 +5-43 | +5-72 | +6-61 || 45:16 15 10 || —1-15 | —3-67 | —6-01 | —4-86 + 5:04 | +5-50 | +6-08 | +4-65 16 10 || —1-22 | —3-87 | —5-72 | —5-04 +4-83 | +498 | +3-71 17 10 || —1-26 | —3-80 | —4-65 | —5-12 +2-62 | +3-96 | +3-28 || +2-52 18 10 || —1-34 | —3-30 | —2-81 | —4-31 +1:14 | +2-49 | +1-55 || +1-22 19 10 | —1-33 | —2-35 | —0-93 | —2-82 | —0-16 | +0-90 | —0-04 | +0-07 20 10 | —1-18 | —0-99 | +0-99 | —0-53 43 | : —0-99 | —1-05 | —1-14 || —0-93 21 10 | —0-32 | +0-87 | +2-51 | + 1-62 : : —1-66 | —2:35 | —2-18 || —1-72 22 10 || +0-77 | +2-70 | +3-72 | +3-59 69 | | . — 2-29 | —3-48 | —2:93 | —2-36 23 10 | +1-84 | +3-88 | +4-88 | +5-03 ‘91 | ‘7 —2-:71 | —4-15 | —3-32 || —2-72 | Intervals. Minimum Maximum ] A.M. .M. P.M. P.M. A.M. Mean |p. M. Mean| a M. Mean} Minimum to to to to Maximum. Maximum.|P.M. Mean.) Sunrise. Noy. Dee. Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Year The following are the conclusions from the previous table :— lst, The minimum temperature occurs immediately before sunrise in summer, about 1} hours before it in winter and spring, and about half-an-hour before sunrise in autumn ; it is evident, however, that accuracy in the determination of the interval is not increased by combining sey eral months together, since, in the result for the year, the minimum appears to occur at a greater interval from sunrise than in any of the quarters. 2d, The maximum temperature occurs latest after noon before the autumnal and after the vernal equinox ; it oceurs nearest noon in summer, but the temperature changes very slowly in that quarter from 1" to 3" P.M. PRESSURE OF AQUEOUS VAPOUR. Ixxxvul 3d, The intervals between the epochs of mean temperature and of the maximum temperature are nearly equal in spring and autumn; the afternoon interval is greatest in summer, and it is least in winter. If we except summer, the temperature increases as rapidly from the mean to the maximum, as it diminishes from the maximum to the mean; the slight difference in autumn between the values of the intervals, and even that in summer may be due to error in the epoch of maximum resulting from the fewness of the observations. In each quarter, with the exception of summer, the temperature diminishes more rapidly after the maximum till sunset than it increased during equal time before the maximum.* It will be seen from the column for the year, in Table 75, that the mean temperature for the pairs of hours before and after 1" and 2 p.m., are equal or nearly equal till the pair 9 10™ a.m. and 6" 10™ p.m., which are also nearly equal, so that the mean diurnal eurve for the year from 9" 10™ «.m. till 6" 10™ p.m. is symmetrical about a vertical axis. PRESSURE OF AQUEOUS VAPOUR. TABLE 77.—Mean Pressure of Aqueous Vapour for each Month in the Years 1843-6. | | Year. Jan. Feb. | March.| April. | May. | June. | July. | Aug. | Sept. Oct. Nov. | Dec. || Mean. | in. in. in. in. in. in. in. in. in. in. in. in. in. 1843 || 0-220 | 0-184 | 0-223 | 0-253 | 0-281 | 0-320 | 0-387 | 0-409 | 0-382 | 0-245 |0-238 | 0-280 || 0-283 1844 ‘216 | -180 | -209 | -258 | -273 | -354 | -367 | -355 | -351 | -276 | -258 | -187 || -274 1845 -203 |--181 | -185 | -251 | -276 | -374 | -358 | -366 | -317 | -297 | -252 | -207 -272 1846 -251 | -249 | -222 | -254 | -298 | -409 | -425 | -443 | -397 | -306 | -269 | -187 -309 Mean +222 | -198 | -210 | -254 | .282 | -364 | -384 | -393 | -362 | -281 | -254 | -215 -285 183. Annual Variation of the Pressure of Aqueous Vapour.—The pressure of aqueous vapour, as deduced from the observations of the dry and wet bulb thermometers, is least in February, being in the mean of 4 years = 0:198 inch of mercury, and it is greatest in August = 0°393 inch, the difference between the greatest and least monthly means being nearly two-tenths of an inch. The mean pressure for each of the four months December to March varies little ; so also for the four months June to September. The mean pressure for the four months December to March from 4 years’ observations = 0°211 inch. PONSA cies slejaceis.e 0 9 9° ole sesnicle eagle lasiefeite » Junestoyseptemberjassa-c.-cs2-ceiia- ++ -easside os) nO oad The mean pressure of aqueous vapour for the 4 years 1843-6 0:285 TABLE 78.—Variations of the Pressure of Aqueous Vapour with reference to the Moon’s Age and Declination for the Years 1843-6. After Moon farthest | North. d. d. 27— 1 2— 5 6— 8 9—12 13—15 16—19 20—22 23—26 eee! eee et ah 184. Variations of the Pressure of Aqueous Vapour with Reference to the Moon’s Age.—Though it has not been possible to determine by our apparatus the heating effect of the moon, yet it is believed that it has some * The difference betwixt this result and that obtained by others is due, it is conceived, to the want of proper precautions to avoid the effects of radiation or reflection of the sun’s heat from the soil or surrounding objects in the afternoon. It will be seen, in the Introductions to the several volumes, that this source of error was cared for at Makerstoun. MAG. AND MET. OBS. 1845 anp 1846. y Ixxxvlii GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. effect, especially on the aqueous contents of our atmosphere ; in order if possible to determine this, the discus- sions, of which the results are contained in Table 78, were made for each year; the means of the 4 years indicate as follows,— 1st, That on the whole, the pressure of aqueous vapour was greater about opposition than about conjune- tion; the average pressure of each of the 15 days forming the second and third quarters beg 0-003 inch above the mean, and of each of the 15 days forming the fourth and first quarters being 0:003 inch below the mean. 2d, That the pressure of aqueous vapour was greatest from about the period of the moon’s farthest southerly position, till near its farthest northerly position ; that it was least from its farthest northerly position till it was nearly farthest south. 3d, If the first result be considered true, then the aqueous vapour pressure varies with the moonlight ; as this pressure is greatest in the months from June to September (No. 183), during which the moon is in con- junction in its ascent from its most southerly declination, and Jeast in the months from December to March, during which it is in conjunction in its descent from its most northerly position, the second result is probably a consequence of the first. TABLE 79.—Diurnal Variation of the Pressure of Aqueous Vapour for each Astronomical Season — and for the Year, deduced from the Observations of the Years 1843-6. May. Aug. Tak. : May. Aug. June. Sept. Year. : . | June. Sept. July. Oct. ime. April. July. Oct. in. | — 0-015 || 3/— -018 — .024 | 025 || 028 | - .030 || -024 -O11 -003 014 019 -022 + Sp. . SF mn Oo [++ Ptt EE [+e eet e Tbe EEE EH KSCOUOUONOAUAHRWNHHYO: +++44 1 185. Diurnal Variation of the Pressure of Aqueous Vapour.—The following are the approximate epochs of the minimum and maximum, as deduced from Table 79. Winter, Nov., Dec., Jan., Minimum, 11) p.w—7? a.m. Maximum, 1? 30” p.m. Springs) y.Hieb:, March; Aiprily jy G2 ase. care ABS OM aM! | | cl soe Ob 40™ p.m. Summer, “May; June, July, 9 9.) 2cs..csee Sg OUNAcM | fy | ecules 1h 30™ p.m. Autumn sy sAursceptsOctwem llesenesssateee SUaOME kar = | eee eee 0» 40™ p.m, Vear ly > Wapi-y MMe eee Abe Om Aca. |b | AAA ECE 1» 10™ p.m. These epochs do not differ greatly from those for the temperature of the air, the principal difference is to be I s ) ; ‘s found in the variation of the epochs of maximum with season; the maximum pressure of aqueous vapour occurs earliest near the equinoxes, and latest near the solstices, whereas the reverse is the ease for the tem- 2 > perature of the air. In the mean for the year, the mean pressure of aqueous vapour occurs at 8" 0™ 4.n., and at 88 25m p.m., the interval being 125 25™. The range of the diurnal variation for the Winter quarter = 0-018 inch. ara bisls a ope ele aetingerssa sole eta infeton Gree Oe CEE PLING 5 Aa ces =2OsO26 ohn di meee Stab tara penne eae Oa Grae oh es SI eee Summer ...... = 0-040 Autumn ...... = 0:054 eo Year = 0-034 si ae : The range of the mean diurnal variation, therefore, gradually increases from the winter quarter till the autumn, when it is largest, the ratio of the ranges for the four quarters being as 6: 9: 13: 18 nearly. This varia- tion of the range is neither related to the range of temperature, nor to the absolute value of the pressure of aqueous vapour. f RELATIVE HumipIvy. Ixxxix RELATIVE HuMIDITY. TABLE 80.—Mean Relative Humidity of the Air for each Month in the Years 1843-6, Saturation being equal to Unity. | Sept. | Oct. | Nov. Dec. || Mean. | = Year. Jan. Feb. | March. April. | May. | Sune. July. | | | Aug. | |- | | | | 1843 | 0-852 | 0-873 | 0-855 | 0-800 | 0-845 | 0-803 | 0-820 | 0-850 | 0-837 | 0-860 | 0-904 | 0-878 | 0-848 1844 || -935 | -882 | -828 | -775 | -768 | -819 | -808 | -818 | -852 | -848 | -882| -941 || -846 1845 || -919 | -857 | -811 | -811 | -831 | -813 | -834 | .835 | -842 | .841 | -875 | -851 || -843 1846 | -896 | -844 | -836 | -859 | -766 | -736 | -834 | -861 | -874 | -890| -897 | -901 | -850 -824 | -841 | -851 | | 832 802 | 186. Annual Variation of the Relative Humidity,—The relative humidity is least in June, and it is greatest ‘| in December and January ; the three months, April, May, and June, have the least mean, = 0°802; the three months, November, December, and January, have the greatest mean, = 0°896, The means for the astrono- mical seasons are as follow :— a Winter, Nov., Dec., Jan., = 0°896 Summer, May, June, July, = 0°806 Spring, Feb., March, April, = 0-836 Autumn, Aug., Sept., Oct., = 0°851 Year, = 0°847, Saturation being equal to Unity. TABLE 81.—Variations of the Relative Humidity with reference to the Moon’s Age and Declination, for the Years 1843-6. After Moon farthest 1843. 1844. 1845, 1846. || Mean. North. | = — + | - — d. d. d. d. | 14—16 || —-008 | +-009 | +-008 | +-011 | +-005 | 27— 1 | —-010 | —.016 | —-007 | —-006 | —-010 17—20 || +-012 | +-012 | +-014 | —-014 | +-006 | 2— 5 | —-003 | —.003 | —-008 | +-003 | —-003 21—24 | +-010 | +-001 | —-010 | —-006 | —-001 | 6— 8 || —-001 | —-001 | +-002 | +-001 | -000 25—28 | +-009 | +-001 | -000 | +-022 | +-008 | 9—12 | —-010 | +-017 | +-009 | —-016 | -000 29— 1 | —-005 | —-014 | —-003 | +-003 | —-006 | 13—15 | +-013 | +-012 | —-001 | +-003 | +-007 2— 5 || —-006 | +-007 | —-003 | —-020 | —-005 | 16—19-| —-025 | —-015 | -000 | +-024 | —-004 6— 9 | +-002 | —-008 +-002 | +-013 | +-002 | 20—22 | +-018 | +-006 4-014 | —-005 | +-008 - ~. = 23—26 | +-017 | —-001 | —-007 | —-004 | +-001 187. Variations of the Mean Relative Humidity, with Reference to the Moows Age and Deelination.—The object of this discussion has been already stated, No. 184; the results here are considerably more indistinct than in the former case ; they agree on the whole, however ; the pressure of aqueous vapour and the relative humidity following nearly the same law ; which might be expected if the temperature of the air be supposed not to vary with the moon’s position. The relative humidity is greatest at and after conjunction; it is least at and after opposition. It is greatest while the moon is ascending from its most southerly position, and least when most northerly. (See No. 184 3d). | | | | | XC GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. ‘TABLE 82.—Diurnal Variation of the Relative Humidity of the Air, for each Astronomical Season and for the Year, deduced from the Observations of the Years 1843-6. Mak. Nov Feb. May. Aug. Mak. Nov Feb. May. Aug. Mean Dec March. | June. Sept. Year. Mean Dec March. | June Sept. Year Time Jan. April. July Oct. Time. Jan April. July Oct. || h. m. h. m. } (pas 12 10 | +0-013|+0-061 |+0-103 |+0-072 |4+ 0-062} 0 10 | —0-035 |—0-090 | —0-109 | —0-106 |—0-085 13 10 ||+ -014\+ -065/+ -105|+ -075|)}+ -065} 1 10 |— :043)— -107|/— -118/— -122)|— .097 14 10 ||+ -012/+ -069|/+ -105|+ -072)+ -064] 2 10 |— -044|)— -110)— -112)— -130)}— .099 15 10 |}+ -014/+ -065|4+ -109/+ -078||+ -066] 3 10 |— -027)\— =106)/— -112|— -120 — -091 16 10 |+ -017\/+ -064|+ -101)/+ -075|)}+ -064] 4 10 ||— -009|— -090 — -102|— .096)\— .074 17 10 |+ -018|/+ -066|)+ -087)+ -072)|}+ -061] 5 10 |+ -001)— -052}— -079 — -.058)}— .047 18 10 ||-+ -022/+ -058|+ -062/+ -064|/+ -051] 6 10 |+ -003/— 027 |- -051}— -016||/— -.023 19 10 |} + -019)+ -050|+ -023)+4+ -052))+ -036) 7 10 |+ -003 [+ -009|— -012 i+ .018\/+ -004 20 10 |+ -021/+ -027/— -017|+ -019\/+ -012] 8 10 |+ -007\+ -028)+ -031)+ -038 + -.026 2110 |+ -007/— -010|— -054|— -019]//— -019} 9 10 |+ -009/+ -037/+ -059 + -051)+ -039 22 10 |— -005/— -054|— -077|/— -057|/— -048}] 10 10 |}+ -007|/+ -053)+ -078 + -060 + -049 23 10 |— -027|— -073|}— -103)/— -085)|/— -072] 11 10 |/+ -004/+ -060\+4 -088 Ss 057 |+ -052 188. Diurnal Variation of the Relative Hunidity——The following are the approximate epochs of maxima and minima, as obtained from Table 82. Winter, Nov., Dec., Jan., Maximum 7" a.m. Minimum 12 50™ p.m, Spring, March; ApiallMiay, 9 seeeeeeerace SRUASME Lee Aeeeeee 12 50™ p.m. Summer, ‘Jue! Sully; sAug.. 0 Cee esse SHUM. Ch ci Sere ae 15 20m p.y. Autumn,’ “Septs*Oct Nov.) © iiss sence 3h aM oo Om Spee Wear, ¢' 2.) lon apeeeeenere hk Na RE 14 40™ pix. The diurnal variation of relative humidity is nearly the inverse of that of the temperature of the air. The mean relative humidity occurs at 8" 33™ aM. , and at 7" 1™ p.m., the interval being 10 28m, The range of the diurnal variation is least im winter, = 0-066 ; it is ereatest in summer, = 0:227; the values of the 1 range for spring being 0179, and for autumn being 0-208. ATMOSPHERIC PRESSURE. 189. The Mean Pressure of the Atmosphere at Makerstoun, 213 feet above the mean level of the sea, as deduced from the observations in the 8 years 1842-9, = 29-615 ‘arches of mercury at 32° Fahrenheit, measured on brass at 62° Fahrenheit ; with a probable error ae 0-009 inch, each year’s mean receiving an equal weight. The mean pressure for any future year = 29-615 inches, with a probable error of 0-026 inch.* TABLE 83.—Monthly Means of the Atmospheric Pressure at Makerstoun, for the Years 1841-9. Ra a a a a a Fa | Mean of 8 Years. | Month. 1841 1842. 1843. 1844. 1845, 1846. 1847 | 1848. 1849 | cs Mean | || Height of ee | | 219 feet.| Level ; | of Sea. in. in. in. in. in. in. in. | in. I in. ie in. Jan. 29.584 | 29-357 | 29-693 | 29-512 | 29.392 | 29-604 29-722 | 29.508 || 29.547 | 29.786 Feb. | 611 -499 -321 704 617 625 | -194| -819 || -549 -788 March | 485 | -662| -529 |. .741 406 775, | «354. |) -755, peo SGnlaesos April 946 | -487| -805 | -642 535 455 | .595| -450 || .614] -850 May -626 | -620 | -980| -703 || -648] -599| -770! -796 || -7aS)1. -Ona June “164).---619)|-627 |x 597 706 |. -672 |. .475 | --735 |} =649 | —-879 July 665 | -635| .625 | -622|] -556] -794/ .619|. .583 || .637 | -865 Aug. ||29-567| -723 | -656| -489| -578| 691 751 526 658 || -634 | -863 Sept. 483 | -652 | -935| -817| -645| 732] -605| -717| -792 | -737 | -970 Oct. || -372] -682 | -401 397 | .602] -312] -646 551 606 || -525 758 Nov. || -453 | .448| 471 563 | | -323 655 | | -643'| 601 530 | 529 765 Dee. || «++ 649 -962 892 369 599 | -490 542 723 || -653 $92 Mean | 653 | -609| -645 586 571 638 555 | -663 | -615 | -846 * All the observations are reduced to the mean of the flint and crown glass barometer of the Royal Society of London. In com- paring these results with others reduced to the flint- glass barometer only, a correction of + 0°003 in. should be applied. See Intro- duction 1844, page lv. ANNUAL VARIATIONS FOR THE ATMOSPHERIC PRESSURE. X¢l 190. Annual Variation of the Atmospheric Pressure.—Eight years’ observations appear insufficient for an accurate determination of this law. If we give the monthly means for each year equal weight, we find the probable error of the means in the last column of Table 83 to be Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Noy. Dec. in. in. in. in. in in. in. in. in. in. . in. in. 0:043 0:045 0:087 0:040 0:028 0-020 0:016 0:021 0:024 0-030 0:025 0-044 The probable errors of the means for the five months December to April are greatest, and they are least for the months June, July, and August. The irregularity of the monthly mean pressure is therefore least at the hottest season, and greatest at the coldest season of the year ; it does not vary, however, with the irregu- larity of the monthly mean temperature. (See No. 178.) It is evident from these probable errors that the accurate epochs cannot be obtained from the last column of Table 83. If we take the means of each couple of months, the probable error of each mean will be reduced to about a half (the probable error of the mean of December and January, = 0°024 inch, of January and February, = 0-019 inch, &c.), and the annual law will be more certain; these means are as follow :— Prefix Jan.—Feb.— March—April— May—June—J uly— Aug.—Sept.—Oct.—Nov.—Dec.—Jan. 29 in. 548 -568 -601 -666 -683 -643 °636 -685 -631 :527 -581 -600 These numbers give nearly the same result as that derivable from the simple means in the last column of Table 83. It is probable, therefore, that at Makerstoun the atmospheric pressure is a maximum from May to September, being rather less for the intermediate months than for the first and last of that period; that it is a minimum in the end of October and in the beginning of February, a secondary maximum occurring in the end of December.* 191. The quarterly groups which give the greatest range of mean pressure are the following,— Jan. Feb. Mar. April, May, June, July, Aug. Sept. Oct. Nov. Dee. Oct.—Mar. Apr.—Sept. in. in. in, in. | in. in. 29°561 29-660 29:°669 29-569 | 29-565 29:°665 * Having examined the excellent series of barometric observations made under the direction of the Astronomer Royal at Greenwich, simultaneously with the Makerstoun series, for the purpose of comparing the annual law at the two places, the conclu- sions are given briefly in this note. 1st, From the means of 9 years’ observations (1841-9) at Greenwich, the atmospheric pressure is amaximum from May to Septem- ber, the secondary minimum seen between these months at Makerstoun being wholly wanting; it is alsoa maximum in December, and, unlike the Makerstoun result, the mean for December is the greatest ; it is a minimum in October and November, as at Makerstoun ; and it is a minimum again in April, about two months after the corresponding minimum for Makerstoun. 2d, When we compare the Greenwich monthly means for the 8 years 1842-9 with the Makerstoun monthly means for the same years, both being reduced to the level of the sea, and to 32° Fahrenheit, we find the barometer at Greenwich higher than at Maker- stoun in each month, and for the whole period as follows :— Jan. Feb. March. April. May. June, July. Aug. Sept. Oct. Nov. Dec. Year. in. in. in. in. in. in, in. in. in. in. in, in. in, 0167 0:133 0-097 0-031 0-014 0-087 0-114 0:097 = 0035 0-112 07140 0146 0-098 Whence it appears that for the same (sea) level, the barometer, on the average of 8 years, is one-tenth of an inch lower at Maker- stoun than at Greenwich, 4° 6’ farther south; and that this difference of pressure varies with the month. The excess of the atmos- pheric pressure at Greenwich over that at Makerstoun is a principal maximum in January, the coldest month; and it is a maximum again in July, the hottest month ; it isa minimum in April and May, and again in September. It may be remarked, with reference to this curious result, that the positions of Greenwich and Makerstoun are much alike; nearly on the same meridian, and nearly equi-distant from the eastern coast of the island. There is no doubt that the greater proximity of Greenwich to the Continent has an effect upon its temperature, the mean temperature of Greenwich being only 2° higher than that of Makerstoun in winter, while it is 5° higher in summer. 8d, From the mean of 8 years the atmospheric pressure at Greenwich is 0-098 inch greater than at Makerstoun, but the excess is by no means constant for each year ; the excesses for each year are,— 1842. 1843. 1844. 1845. 1846. SA 7 we 1848, 1849. in. in. in. in. in. in. in, in. 0-119 0:096 0:070 0:096 0-102 0-116 0:104 0:079 The excess varies as much as half its mean value, and appears, on the whole, greatest in the hottest years and least in the coldest. 4th, The following coincidences may be mentioned. The epochs of the annual law of mean atmospheric pressure (especially those for Greenwich) are nearly the same as for the annual law of magnetic declination (No. 9); and the law of differences of pressure for the two places has nearly the same epochs as the annual law for the magnetic force (No. 136). MAG. AND MET. oBs. 1845 anp 1846. z XCll GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS The mean pressure for the six months October to March is 0-100 inch less than that for the six months April to September, while the range of the quarterly groups for the meteorological seasons is only 0-057 in. Neglecting therefore the minor variations, the law of atmospheric pressure is distinguished by a maximum for the six months during which the sun is north of the equator, and a minimum for the six months during which it is south of the equator. The means for the separate quarters show no direct connection with temperature, since April to June, and July to September have nearly the same mean pressure. . TABLE 84.—Mean Differences of the Daily Mean Atmospheric Pressure from the Monthly Mean, for each Month in the Years 1843-6. Feb. | March. | liMean! in. 0-281 274 °145 in. 0-261 -310 +208 -255 | +325 -239 “276 | 192. Annual Variation of the Differences of the Daily Mean from the Monthly Mean Pressure.—From the means for four years in Table 84, the daily mean pressure of the atmosphere varied most in the months of November and January, and it varied least in July. The following groups give the greatest and least quarterly means,— Nov. Dec. Jan. Feb. Mar. April, May, June, July, in. in. in, 0°300 0°258 0-208 Aug. Sept. Oct. in. 0:246 The daily mean height of the barometer differs on the average three tenths of an inch from the monthly mean in the winter quarter, Nov.—Jan., and only two tenths of an inch in the summer quarter, TABLE 85.—Monthly Means of the Diurnal Ranges of the Atmospheric Pressure for the Years 1843-6. Year, Jan. Feb. | March,| April. | May. | June. | July. | in. in. in. in. in. in. in. ieeeins in. in. | in. in. in. 1843 | 0-342 | 0-180 | 0-206 | 0-235 | 0-151 | 0-169 | 0-194 0-166 | 0-165 | 0-285 | 0-355 0-207 0-221 1844 -224 | -282 | .298 | -185 | -124 148 | -156 | -181 -134 | -234 -196 | -145 -192 1845 +320 | -243 | -236 | -222 | -131 184 | -181 | -164 |. -223 -208 | +269 452 -236 1846 || -283 | -202] -269 | -160 | -183 |) -142 172 | 149 | -165 94 | > | | Mean || -292 | -227 | -252 | -200| -147 161 | -176 | 193. Annual Variation of the Diurnal Range of the Atmospheric Pressure——From the means of the diurnal ranges for each month in the four years 1848-6, the diurnal range is least in May, and it is greatest in January ; the following groups give the greatest and least quarterly means,—— Noy. Dee. Jan. Keb. Mar. April, Aug. Sept. Oct. in. in. in. in. 0-269 0226 0-161 0 197 May, June, July, MonTHLY VARIATIONS FOR THE ATMOSPHERIC PRESSURE. xX¢lil The monthly mean diurnal range does not vary greatly in the six months for which the sun is south of the equator, nor in the six months for which it is north of the equator; thus, the mean range for the six months October to March = 0-257 in., and for the six months April to September = 0°170 in. On the whole, the diurnal range varies inversely with the monthly mean pressure. See No. 197 where the ranges of the mean diurnal variations are considered. TABLE 86.—Variations of the Diurnal Range of Atmospheric Pressure, with reference to the Moon’s Age and Declination for the Years 1843-6. | in. d d. in. in. in. in. in. * in. in. in. 14—16 ||+-012|—-032)—-063 | —-027 |—-027] 27— 1 |+-031]+-019 | +-026 |+ -022)+-025 After | Moon’s E Moon | Age. 1843. | 1844. | 1845. | 1846. || Mean. | faythest || 1843. | 1844. | 1845. | 1846. | Mean. | North. | a I. d. d | 17—20 |--014) -000 +-049) -000}+-009] 2— 5 | +-010]+-022 —-006 +-004) +-008 21—24 ||—.034/+-017/+-069 |+-030||+-021] 6— 8 ||—-001|+-009 |—-005 |—-053 ||—-012 25—28 ||+-001 |—-001|—-009 | —-003||—-003] 9—12 ||+-010|—-018|—-021 |+-010||—-005 29— 1 ||+-030 |+-024/+4-005 |+-005 ||+-016] 13—15 | —.032]—-026|+-019|+-009| —-008 2— 5 |+-010 +-011 +-002 +-019 /+-011] 16—19 | —-028]—-007 | —-003 | — -002 | —-010 6— 9 ||+-001 |+-026|—-011 | +-008 | +-008| 20—22 |.+-015|—-015 | —-033 |—-005 ||--010 10—13 ||—-007 |—-044 |—-045 | —-033 ||—-032| 23—26 4-019 || +-015 | ro) S wo + =) = > + =) vo ro) 194. Variation of the Diurnal Range of Atmospheric Pressure with the Moon's Age.—Investigations have been entered into by different meteorologists for the purpose of exhibiting the effect of the varying position of the moon upon the mean daily pressure of the atmosphere ; their success has been on the whole very doubtful. In our latitudes it is not easy to extricate the laws of these variations on account of the magnitude of the irregular changes ; it was for this reason that, after discussing the daily mean pressures for the year 1843 with refer- ence to the lunar arguments, the discussion of the diurnal ranges was substituted for that of the daily means ; as it was conceived that the variation of the diurnal range might be considerable (as in the case of the oceanic tides, &c.), though the variation of the mean should be nearly or altogether zero ; such had been found to be the case for the magnetic declination. The results of these discussions for each year, and for the mean of four years, are given in the first part of Table 86. The results for the four years are wonderfully consistent, and that of the mean of the four years may be expressed thus.—The diurnal range of the barometer is a minimum near opposition, and it is a maximum about the beginning of the second quarter, and immediately after con- junction ; perhaps the intermediate minimum near conjunction is accidental and might disappear in a larger series. The range of these mean numbers is very considerable, upwards of half-a-tenth of an inch, and it is probable that had the means for single days of the argument been given, the range would have been nearly twice as great. This result is wholly different from what we should have expected when comparing the oscillation of the atmosphere with that of the ocean, and it appears difficult to offer an explanation for it ; we shall find how- ever when we examine Table 91, that it is probably connected with the force of the wind; at least that obeys the same law, the diurnal range of the barometer being greatest when the force of the wind is greatest. 195. Variation of the Diurnal Range of the Atmospheric Pressure with Reference to the Moon’s Declina- tion.—The values for four years for this argument are given in the second part of Table 86; the results for each year agree here also to a remarkable extent with that shewn by the mean of the whole four years. The diurnal range of the barometer is a maximum when the moon is farthest north, it is a minimum when the moon is south of the equator. This result is also connected with that for the force of the wind (see No. 201), the diurnal range of the barometer being greatest when the force of the wind is greatest, and vice versa. XC1V GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 4 TaBLE 87.—Diurnal Variation of the Atmospheric Pressure for each Astronomical Season and for the Year, deduced from the observations of the Years 1843-6. pHt++ 444i | + S f=) er) (or) Table 87 has been formed thus :—The hourly means for each quarter were obtained for each year ; those for 1844 and 1845 were corrected for continuous barometric change as described in the volume for 1844, p. 422, excepting that the change of pressure from 11" to 12", was considered equal to the mean of the changes from 10 to 11" and from 12" to 1", (instead of from 10" to 11" only): the hourly means for each quarter were then combined in the manner already described for the magnetic declination, No. 26. TABLE 88.—Daily Epochs of Maximum and Minimum Atmospheric Pressure, with the Intervals from Epoch to Epoch, for each Quarter, and for the Year. Interval Interval Interval Interval Mean Epoch betwixt from from from Pood: Minimum An Mae Minimum Min. Maximum Maas the Two A.M. i is P.M, AS P.M. Min. Me Maxima. | Minima. Nov. Dec. Jan. 3 40 | Feb. Mar. Apr. | 4 15 | May June July : 8 45 Aug. Sept. Oct. | 4 6 50 Year | 2 5 30 196. Diurnal Variation of the Atmospheric Pressure-—From Table 87, this consists of two maxima and two minima in each quarter of the year: the approximate epochs in apparent time, as deduced from the projee- tions of Table 87 (see Plate IX.), are given in Table 88. ist, The principal maximum occurs in the evening in spring, and in the forenoon in the other quarters ; the principal minimum occurs in the morning in winter and spring, and in the afternoon in summer and autumn. 2c, The morning minimum occurs earliest in summer and latest in winter, obeying something like the law of sunrise, though the difference of epochs is variable, the minimum occurring about 3 hours before sunrise in winter, and immediately before sunrise in summer: the epoch of minimum temperature had a nearly similar relation to that of sunrise, but the similarity of the relations of the two classes of facts is more apparent than real, since the temperature of the air varies little in winter from 6" p.at. till 8 a.m, 3d, The morning maximum occurs latest in spring and earliest in summer, the difference of the epochs for the two seasons being nearly three hours, PRESSURE OF THE WIND. Xcev 4th, The afternoon minimum occurs earliest in winter and latest in summer, the difference of the epochs ‘being nearly three hours. The epochs of this minimum have some relation to those for sunset as the morning minimum epochs had to sunrise, thus :—In winter, the morning minimum occurs about three hours before sunrise, in summer the afternoon minimum occurs about three hours before sunset; in winter the afternoon minimum occurs about one hour and a half before sunset, in summer the morning minimum occurs about half- an-hour before sunrise. 5th, The afternoon maximum occurs latest in summer and earliest in spring; the difference of the epochs is two and a half hours. 6th, It is not easy to relate the variations of the epochs of the maxima to those of any other facts ; itis to be observed, however, that the morning maximum occurs nearest noon in spring and farthest from noon in summer, while the afternoon maximum occurs farthest from midnight in spring and nearest midnight in summer. TABLE 89.—Whole Amount and Hourly Rate of the Change of Atmospheric Pressure from Epoch to Epoch in the Diurnal Variation for each Quarter, and for the Year. A.M. Minimum to | A.M. Maximum to } P.M. Minimum to | Pp. M. Maximum to A.M. Maximum. P.M. Minimum, Pp. M. Maximum. A. M. Minimum. Whole Oscillations. Period. Total. |Per Hour.| Total. |Per Hour.}| Total. |Per Hour.| Total. {Per Hour.|| Sum. {Per Hour. in. in. in. in. in. in. in. in. in. in. Nov. Dec. Jan. || 0-0308 |0-0060 | 0-0160 | 0-0044 | 0-0126 |0-0018 | 0-0275 | 0-0033 || 0-0869 | 0-0036 Feb. Mar. Apr. || -0210 | -0030 | -0140 | -0033 | -0180 | -0035 | -0250 | -0033 -0780 | -0033 May June July -0139 | -0018 | -0230 | -0026 | -0191 ‘0031 |} -0100 | -0024 -0660 | -0027 Aug. Sept. Oct. | -0166 | -0035 | -0208 | -0030 | -0188 | -0031 | -0146 | -0023 | -0708 | -0030 Year -0180 | -0029 | -0150 | -0027 | -0145 | -0026 | -0173 | -0026 || -0648 | -0027 197. The total oscillations from one turning point to the next are given in Table 89, with the hourly rate of change; from these, we find that the change of pressure, from the morning mmimum to the morning maximum, is greatest in winter and least in summer ; from the afternoon mimimum to the evening maximum, it is least in winter and greatest in summer ; from the morning maximum to the afternoon minimum, it is least in spring and greatest in summer; from the evening maximum to the morning minimum, it is greatest in winter and least in summer. On the whole, when we compare the diurnal variations with respect to season, both as to the epochs and relative amounts of the oscillations, from turning point to turning point, we arrive at the fol- lowing conclusion :—1st, That the law of diurnal variation of atmospheric pressure at Makerstoun, is almost precisely the same in winter as it is im summer, if we substitute noon for midnight, and pM. for a.m, in the former.* 2d, As the diurnal variation for spring is analogous to that for winter, and the diurnal variation for autumn is similar to that for summer, the same law of opposition holds for spring and autumn as for summer and winter. See Plate IX. 3d, The whole diurnal oscillation is greatest in winter, and it is least in summer. PRESSURE OF THE WIND. 198. In the volumes for the years 1843 and 1844, both the maximum pressures of the wind occurring betwixt the hours of observations and the observed pressures within 7™ to 10™ at the hours of observation were discussed ; as both discussions gave the same results, and as the latter make an approximation to the actual continuous mean pressures, only the means of the pressures occurring within 7™ to 10™ at the hours of obser- vation will be considered here. * This curious fact, it seems to me, is wholly opposed to what may be termed the temperature theory of the regular diurnal variation of atmospheric pressure ; the best marked barometric oscillation at Makerstoun occurs while the temperature and pressure of aqueous vapour are nearly constant, namely, in winter between 6" P.M, and 9% A.M. MAG. AND MET. OBS. 1845 AND 1846. 2a Xevl GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. TABLE 90.—Monthly Means of the Maximum Pressure of the Wind within 10™ at the Observation Hours for the Years 1843-6. March.| April. | May. | June. 199. Annual Variation of the Approximate Mean Pressures of the Wind.—From the means of 4 years’ observations, the wind blew with the greatest mean force in January, and with the least mean force in Septem- ber. The mean pressure, however, varies little for the six months October to March, while the sun is south of the equator ; it is nearly constant for the three months, April, May, and June, diminishing gradually from June to September. September is the month of least pressure in each year, excepting 1844; the month of maximum pressure is more variable, January in 1843, November in 1844, December in 1845, and March in 1846. TABLE 91.—Variations of the Pressure of the Wind with reference to the Moon’s Age and Declina- tion for the Years 1843-6. After Moon’s Moon | x Age. 1843. 1844, 1845. 1846. fanthvest 1845. 1846. North. ders | 27— 1 2— 5 6— 8 | 9—12 13—15 16—19 20—22 | 23—26 200. Approwimate Mean Pressure of Wind with Reference to the Moon’s Age—The mean result from the first portion of Table 91 shews, that the pressure of the wind was a maximum at conjunction and a minimum near opposition. The result for each year shews a well-marked minimum near opposition, and a maximum near conjunction. It has already been noticed (No. 194), that the diurnal range of the atmospheric pressure obeys a similar law ; that is to say, for this argument, the diurnal oscillation of the statical pressure of the atmosphere is &@ maximum when its dynamical pressure is a maximum, 201. Approwimate Mean Pressure of the Wind with Reference to the Moon’s Declination —From the last column of Table 91, the mean result of 4 years’ observations, it appears that the pressure of the wind is a maximum when the moon is farthest north. This result is shewn with some distinctness in each year, excepting in 1848, for which the maximum occurs when the moon is farthest south ; there is, however, the appearance of a maxi- mum near the time of the moon’s farthest southerly position in the years 1845 and 1846; and, indeed, in the mean for the 4 years ; it is probable therefore that the minimum pressure of the wind oceurs when the moon is near the equator. The same relation, between the diurnal oscillation of the statical pressure of the atmos- phere and its dynamical pressure, holds as in No. 200. DIURNAL VARIATIONS OF THE PRESSURE OF THE WIND. xevli TABLE 92.—Diurnal Variation of the Maximum Pressure of the Wind within 10™ at the Observation Hours, for each Astronomical Season and for the Year, deduced from the Observations of the Years 1843-6. Mak. || Nov., Feb., May, | August, Mak. Nov., Feb., May, | August, | Mean || Dec., March, June, Sept., Year. Mean Dec., March, June, Sept. || Year. Time. | Jan. April. July, Oct. Time. Jan. April. | July. Oct. | | ahd ea [he Aaa, \] calies aa! A “a h. m. | Ib. lb. lb. lb. 1b. I m. lb. 1b. lb. lb. Ib. 12 10 || —0-07 | —0-21 | —0-20 | —0-12 || —0-15 10 | +0-13 | +0-25 | +0-23 | +0-17 |) +0:19 13. 10 || —0-10 | —0-15 | —0-19 | —0-08 || —0-13 10 | +0-11 | +0-29 | +0-27 | +0-22 || +0.22 | —0-13 | —0-14 | —0-21 | —0-09 || —0-14 15 10 | —0-03 | —0.08 | —0-22 | —0-10 || —0-11 16 10 | —0-05 | —0-10 | —0-18 | —0-10 | —0-11 17 10 | —0-02 | —0-12 | —0-15 | —0.09 || —0-09 18 10 | —0-05 | —0-.08 | —0-11 | —0-09 | —0-08 19 10 | —0-05 | —0-10 | —0-03 | —0-10 | —0-07 20 10 || —0-03 | +0-03 | +0-13 | —0-04 || +0-02 21 10 | +0-04 | +0-11 | +0-17 | +.0-07 | +0-10 22 10 || +0-07 | +0-21 | +019 | +0-15 || +0-15 23 10 | +0-11 | +0-24 | +0-23 | +0-20 | +0-19 10 || +0-06 | +0-32 | +0-28 | +0-19 || +0.21 | +0-02 | +0-26 | +0-25 | +0-14 || +0-17 10 | —0-03 | +0-14 | +0-18 | +0-11 | 40-10 | +0-02 | +0-03 | +0-14 | +0-02 || +-0-.05 10 || —0-03 | —0-05 | +0-03 | —0.05. || — 0.02 10 | —0-01 | —0-15 | —0-06 | —0-07 || —0.07 = (0-19) "0-113 | — 0: 107 || —.0-10 10" | —0:02° |= 0-14) |= 0519: |= 0-10" | — 0:11 LO) || +30:02)| 0-162] —0:21,| —0-13 ||, — 0:12 10 || 0-00 | —0-21 | —0-19 | —0-08 || —0.12 ° + 2 S Ne) RF OCOUOONOUKhWwWNr OF — oO Se | 202. Diurnal Variation of the Mean Pressure of the Wind.—It is evident from the means in Table 92, that 4 years’ observations are too few to destroy the irregularities produced by the large atmospheric disturb- ances ; the following, however, are the approximate epochs of maximum and minimum :— Minimum. Mean. Maximum. Mean. Winter, Nov., Dec., Jan., 2 10™ a.m. 8) 36™ a.m. OP 10™ p.m. 3 p.mM.—I11> p.m. Spring, Feb., March, April, 112 40™ p.m. 7® 56™ a.m. 1250" Pear, 5» 32m p.m. Summer, May, June, July, 9 p.m.—4" a.m. 72 21™ a.m, 1h 45™ p.m, 6» 30™ p.m. Autumn, Aug., Sept., Oct., 85 p.M.—7> a.m. 85 32™ a.m. 12 0™ p.m. 5) 27™ p.m. Year, 12 a.m. Or AGM. 1» 30™ p.m. 5) 53™ p.m. It will be seen that the variation of the pressure of the wind obeys a law analogous to that of the variation of temperature, while the sun is above the horizon ; it follows the ascent and descent of the sun, however, more closely than the temperature: thus, in winter the mean pressure of the wind occurs almost exactly at sunrise and at sunset, and the maximum occurs immediately after mid-day, in all instances anticipating the correspond- ing epochs for the temperature by an hour or more. A similar difference is observable in each quarter ; this will be seen most satisfactorily in Plate 1X., where the dotted curves of wind pressure are projected on the same mean or zero lines; as the curves for the temperature of the air: while the day portions of the curves are evi- dently connected with each other, this is not the case during the night ; the minimum pressure of wind has upon the whole the same relation to midnight that the maximum has to mid-day. In winter the pressure varies irregularly from hour to hour during the night; in summer and autumn the pressure is nearly constant for some hours before and after midnight. When we consider the mean for the year, we find the ordinates of equal value in the day portion of the curve at times equidistant from 1" p.m., and in the night portion of the curve, from 1 a.m.: the pressure of the wind, therefore, is related more directly to the position of the sun than to the temperature of the place, especially during the night. The range of the mean diurnal variation is least in winter, and it is greatest in spring and summer—the ranges are— Winter = 0:26 Ib. Spring 0°53 Ib. Summer 0°50 Ib. Autumn 0°35 Ib. Year 0:37 Ib. XeVili GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. TABLE 93.—Number of Observation Hours in 24 at which (within 10™) the Wind blew with a force of 0-1 lb. or upwards, for each Month in the Years 1843-6. Year. Jan. Feb. | March.| April.| May. | June. | July. 1843 18-0 | 16-2] 11-6 | 12-9 | 15-3 |. 17-7 | 14-7 1844 8-6 | 12-3 | 14-7] 14-3 | 10-2 | 16-0 | 11-3 1845 14-4 | 18-7 | 20-3 | 16-2) 20-7 | 18-3 | 17-8 1846 15-9 | 16-8 | 14-6 | 17-2 | 19-5 | 15-7 | 21-0 Mean || 14-2 | 16:0 | 15-3 | 15-1 | 16-4 | 16-9 | 16.2 203. Annual Variation of the Number of Observation Hours at which the Wind was observed to blow with a force of 0-1 lb. or upwards.—Four years’ observations are evidently insufficient to shew this annual variation free from irregularity. The wind blew during the greatest number of hours in October and in June, and it blew during the least number of hours in January. See Table 93. TABLE 94.—Mean Pressure of the Wind while blowing, for each Month in the Years 1843-6. ke owl oO p i=} wy a ae “J Or or co 204. Annual Variation of the Mean Pressure of the Wind while blowing—We have in No. 199 consi- dered the annual variation of the mean pressure of the wind with reference to time, the sums of the observed pressures being divided by the whole number of observations ; in the present case the sums of the observed pressures are divided only by the number of observations for which the wind was blowing: thus, in November 1848, the wind was observed blowing at little more than half the whole number of observation hours ; conse- quently the mean pressure with reference to the whole number of observations for that month (Table 90) is only a half of the mean pressure with which the wind was observed blowing (Table 94). The law is the same for both means, but it is better marked in the present case than in that of No. 199. The wind blows with the greatest force in January, and with the least force in September. 205. Diurnal Variation of the Number of Observation Hours at which the Wind was observed blowing. —The following are the mean numbers of times, at which the wind was observed blowing 0:1 1b. or upwards, in the four years 1843-6 :— 12h bay, gh gh 4h 5h Gh 7h gh gh yoh yh oh Jhpa, gh gh gh 5h Gh 7h gh gh oh 43h 150 156 155 164 162 163 176 190 214 224 242 251 262 266 266 258 249 240 225 211 186 169 162 160 The wind blew most frequently at 1" 40™ p.m, the epoch of maximum temperature ; it blew seldomest about 1} a.m. 206. Diurnal Variation of the Mean Pressure of the Wind while blowing (see No. 204). The following are the means for each hour, as deduced from the observations for the four years 1843-6 :— 1h wham, 22 gh gh ph 6h 7h gh gh yoh yah ob Ybpa, Qh gh gh 5h gh fh gh gh joh Jie Ib. ee ye RT I AU A as Rh Ib. Ib, Ib Jb. Ib. TR To. Tb. be bao 067 067 0:65 0:69 0:70 0:71 0:67 0:64 0°70 O77 O78 0:80 O78 O80 O80 0:75 0:70 067 O61 0:58 O61 0°65 0:67 0°69 PRESSURE AND DIRECTION OF THE WIND. XC1X These numbers still present several irregularities ; on the whole, however, the wind blows with the oreatest force about 1" p.m., and with the least force about 7 p.m., or about an hour after noon and an hour after sunset respectively ; another minimum of force occurs at 7> A.m., an hour after sunrise, and a secondary maximum occurs between 11? p.m. and 5" a.m., the exact epoch is not deducible from these means; the means for 1844 and 1845 only, place it near midnight. 207. Yearly Mean Value and Direction of the Resultant Wind.—From the last line of Table 95, it appears that the direction of the resultant wind was nearly constant in each of the three years, 1843, 1844, and 1845.— 1846 appears to have been quite anomalous; in each of the former years there are eight or nine months in which the resultant wind blows from between west and south, for only two or three of these months is the resultant nearer south than west ; but in 1846 there are ten months, for which the resultant wind blows from between south and west, and for eight of these it is nearer south than west. If we neglect the year 1846, the winds at Makerstoun are equivalent to one continuous wind blowing from nearly WSW. with a force approximately of about two-tenths of a pound on a square foot of surface. TABLE 95.—Values and Directions of the Resultant Winds, with the Sums of the Pressures of the Wind resolved into the four Cardinal Points of the Compass, for each Month of the Years 1843-6. 1843-6. | Sums of Pressures ob- Month. Resultant. Resultant. Resultant. Resultant. ces ane toe “T00 Resultant. Days in each Month, resolved into Mean.| Direction. | Mean.| Direction. | Mean.| Direction. | Mean.| Direction. INE E. S. | W. || Mean. | Direction. 1b. © lb. o 1b. © 1b. 2 1b. lb. 1b. Ib. lb. o f Jan. 0:93} W. 17S. | 0-27) W. 8S. | 0-36] S. 29 W.| 0-37] S. 43 W.1172) 45] 700] 933 || 0-43 | W. 29-5 'S. | Feb. 0:43|N. 8 W.| 0:14) W. 37 N.| 0:22) W. 9S. | 0-38] W. 34S. || 534] 161 | 408 | 565 || 0-18! W. 17-3 N. | Mar. 0:04] S. 31 E.| 0-20) W. 5 N.| 0-39) W. 2S. | 0-52] S. 38 W.|| 332] 153 | 580/667 || 0-24] W. 26.3 S. | April 0:26) W. 23S. | 0-35) W. 328. | 0-15) N. 7 E.| 0-21| N. 24 E. || 423 | 174] 406 | 423 || 0-10} W. 3-9 N. } May 0-20) E. 4N.] 0-16| N. 24 EB.) 0-28) N. 11 BE. | 0-32) S. 44 W.| 446 | 377 | 313/317 | 0-06) N. 24.2 BE. | June 0-12) N. 4E.| 0-34] W. 20S. | 0-34] S. 44 W.} 0.30] S. 39 W.]|| 223 | 133 | 540 | 549 |) 0-22) W. 37-48. | : July 0-29| W. 37S. | 0-06| W. 4 .N./} 0-13} W. 43S. | 0-38] S. 44 W.|} 140; 88 | 445 | 451 '| 0-20] W. 40-0 S. Aug. 0-18] S. 26 W.| 0-18] W. 15S. | 0-16] W. 29 N.| 0-07] S. 30 W.| 186} 79 | 292|332)] 0-11] W. 22.75. | Sept. 0:06| W. 24 N.| 0-07! W. 33 S. | 0-15} W. 29 S. | 0-05] S. 34 W.| 161} 111 | 238 | 267 || 0-07} W. 26-1 S. Oct. 0-19| W. 18S. | 0.23 . 43 W.) 0-45] W. 348. | 0-08} W. 35S. || 249} 156 | 543 | 613 || 0-23} W. 32-88. | Nov. 0:33| W. 24S. | 0-14] S. 23 E.| 0-44] S. 32 W.| 0.28] S. 15 W.| 176] 192] 7051505 || 0-26; S. 30-7 W.! Dec. 0-69| W. 40 S. | 0-06) BE. 30S. | 0-69} W. 168 0.24| N. 40 W.]| 262] 421]546]790 | 0-33] W. 20-88. | Year || 0-20| W. 21S. | 0-13} W. 21S. | 0-231 W. 23S. | 0-19] W. 41S. | 274] 143 | 477/535 | 0-18) W. 27-38 208. Annual Variation of the Force and Direction of the Resultant Winds.—The details of these discus- sions will be found in pages 64 and 84 of this volume, p. 295, 1843, and p. 434, 1844. From Table 95, it appears that— 1st, The sums of pressures of the northerly winds are greatest in the months of February, March, April, and May; they are least in the months of July, August, September, and November. 2d, The sums of pressures of the easterly winds are twice a maximum and twice a minimum in the year; they are a principal maximum in May, and a secondary maximum in November ; they are a minimum in July _ and August, and in December and January. 3d, The sums of pressures of the southerly winds are greatest in November and January, and they are _ least in September. 4th, The sums of pressures of the westerly winds are greatest in December and January, and they are least - in September. 5th, When we examine the approximate mean forces of the resultant wind for each month, we find that on _ the whole they exhibit two maxima and two minima in the course of the year. The resultant wind is a principal maximum in January, and a secondary maximum in June and July; it is a minimum in May and in September. 6th, The direction of the resultant wind is from 17° north of west in February, from 4° north of west in | April, from 24° east of north in May, and from between west and south in the remaining nine months of the year. MAG. AND MET. oBs. 1845 anp 1846. 26 c GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. Of the nine months in which the resultant wind is from between west and south, there are eight, for which it occurs between W. 20° S., and W. 40° S., or nearly between WSW. and SW.; in November the resultant wind is most southerly, coming from W. 59° S. nearly SW by S. 209. If we compare the mean of the pressures observed in all directions (last line of Table 90), in each month, with the resultant mean pressure of the wind, the ratio will evidently give some measure of the varia- bility of the wind; where, by variability is meant the amount of opposedness of the masses of air in motion during the period considered, without relation to the frequency of the oppositions ; the ratios are for each month as follow :— Jan. Feb. Mar. April, May, June, July, Aug. Sep. Oct. Noy. Dee. 1:5 31 2°3 4:6 7:5 2:0 17 2°5 a4 2-2 2°0 16 Of the whole amount of air in motion during each month, the greatest proportions proceed from one quadrant or direction in December and January, the coldest period of the year, and also in July, the hottest month of the year ; the winds are most equally distributed in all the quadrants in the months of April and May; a secondary maximum of variability occurring again in September. 210. Diurnal Variation of the Resultant Mean Pressure of the Wind—The following are the values of — the resultant mean pressure for each hour, as deduced from the observations for the years 1843-6 :— 12h Jhamw, gh 3h 4h 5h gh 7h gh gh igh phi Oh phipar, Qh gh: gh + 95h gh = “ghuwegh oh» qohe aH lb. Ib. Ibs Ibs bs Ibe 2b. Sib) lbs, bebe elbeeeelben albye l1b.. Ib.) )lbSeun]b-a86] batts baie b Sane! beeen Doane 015 0:15 0:16 0:17 0-17 0-17 0:16 0:16 0-21 0:23 0:25 0-25 0:25 0-27 0-24 0-21 0-19 0-18 0-15 0:15 0°15 0-15 0-15 0-16 From these means the maximum occurs before 1" p.m., and the minimum occurs between 6" p.m, and 12 a.m. 211. Diurnal Variation of the Direction of the Resultant Wind,—It was first pointed out in the volume of Makerstoun Observations for 1843, p. 300, that the direction of the resultant wind had a diurnal variation, being more towards the south of west in the morning and evening than about mid-day; this result was con- firmed with great distinctness in the discussion of the Observations for 1844 (vol. 1844, p. 438, and Plate XVI.) ; an equally distinct result has been obtained from the observations for 1845 (p. 64 of this volume) ; this has not been the case with the observations for 1846, a year which, when compared with the others, was ano- malous in all its resultant directions (see No. 207). The following Table contains the means of the resultant directions of each month for the years 1844 and 1845, and for the four years 1843-6, each year receiving an equal value, and the means for the four years being obtained, as described No. 26. * TABLE 96.—Diurnal Variation of the Direction of the Resultant Wind. Mean of Mean of 1844-5. 1843-6. 5. 1843-6. PRDRNNNNNP PNP KHOONDTIAUNBRWNR OF DNADDADD NAD ADNADANDDAND Di ANDNNADNNAD 1 (SU VRS STs NO | —_— The range of the variation for the four years 1843-6 is somewhat diminished by the anomalous numbers for 1846; but both series agree in shewing the resultant wind to be most westerly about 3" p.a., and most southerly between 8" p.wt. and 4! a.m. PRESSURE AND DIRECTION OF THE WIND. Ci 212. The following numbers are the ratios for each second hour of the hourly mean pressures observed in all directions (obtained from the year-column of Table 92, by the addition of 0:46, the mean pressure for the 4 years), to the resultant mean pressures, No 210, 2h 2) aM, 4h 6h 8h 105 Oh 2) P.M. 4h 6h gh 105 al Zell PAL 2:3 2°3 2°4 2°6 2°8 2°9 2°8 2-4 2.2 We may conclude, as in No. 209, that of the total mass of air in motion at each hour, the greatest proportion was from the same quadrant or direction at 25 a.m., and the greatest proportion was from opposite directions at 42 p.m. 213. Times which the Wind blew from the 16 Principal Points of the Compass.—The times which the wind was observed blowing from each point of the compass, at the observation hours, are given for each year m the previous and in the present volume; for 1843 and 1846 the sums for 12 two-hourly observations are given, having doubled these to make them comparable with the means from the hourly observations of 1844 and 1845, the sums for four years for each point were obtained: the sums for each of the 16 principal points were then formed in this manner ;—the sum of the times in the north was made equal to half the sum of the tumes in N by W., plus half the sum of the times in N by E., plus the sum of the times observed in N. ; and similarly for each of the other 16 points.* The sums thus obtained from the four years’ observations are as follow :— N. NNE. NE. ENE. E. ESE, SE. SSE. S. ssw. sw. Wsw. W. WNW. NW. NNW. 779 =«-1318 ~—:1668 867 431 177 329575 1088 2672 4212 - 1949 1198 726 932 866 The wind blew most frequently with a pressure of 0-1 lb., or upwards, from a few degrees south of SW., the _ number of times diminishes rapidly to WNW., increases slightly in NW., diminishes from thence to N., it then increases considerably to a few degrees north of NE., where the secondary maximum occurs almost diametri- _ cally opposite to the principal maximum of frequency ; from NE. the frequency diminishes to a few degrees south of ESK., where it is a principal minimum, a secondary minimum occurring in the opposite point; from ENE. the number increases rapidly to the maximum at SW. See curve 6 in the figure. Radial scales. a, 1 inch = 2000 lbs. 6b, 1 inch = 2000 times. c, 1 inch=1 Ib. * The combination into the 16 principal points was rendered necessary by the fact, that in observing the direction of the wind _ from an oscillating vane-index, there is a tendency in all cases of doubt to prefer the principal to the secondary point, for which reason the numbers of observations for each of the 16 principal points were always greater than for either of the two adjacent points. cu GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. 214. Sums of the Pressures with which the Wind blew from each of the 16 Principal Points of the Com- pass.—Following the same procedure as in No. 213, we obtain the following sums of pressure from four years’ observations, of 24 a-day, the sums being of the maximum pressures observed within 10™ at the hours of obser- vation. (See No. 198.) N. NNE. NE. ENE. E. ESE. SE. SSE. Ss. SSW. SW. WSw. W. WNW. NW. NNW. lb. lb. lb. Ib. Tb. lb. lb. lb. Ib. Ib. Tb. lb. lb. Ib. Ib. Ib. 711 757 722 442 217 84 163 362 749 1945 3411 1262 990 693 689 654 The sums of pressures obey nearly the same laws as the frequency with which the wind blew; the greatest sum of pressures occurred a few degrees south of SW.; the sum then diminishes to W., varies little from WNW. to N. being, on the whole, less at NNW. than for the adjacent points ; it becomes a secondary maximum about NE. by N., a principal minimum at ESE. (See curve a in the figure, p. ci.) 215. Mean Pressure with which the Wind blew from each of the 16 Principal Points of the Compass.—Di- viding the sums of pressures for each of these points (No. 214) by the number of observations for which the wind was observed blowing at 0-1 Ib., or upwards (No, 213), we obtain the following mean pressures with which the wind blew from each of the 16 points :— N. NNE. NE. ENE. E. ESE. SE. SSE. S. SSW. SW. wsw. Ww. WNW. NW. NNW. Ib. lb. Ib. lb. lb. lb. Ib. lb. lb. lb. lb. lb. lb. Ib. Ib. Ib. 0-91 057 O43 051 0°50 0-47 =0°50 0:63 0°69 0-73 0°81 0°65 0°82 0-95 O74 O75 The wind blew with the greatest force from WNW. and N., and with the least force from NE. and ESE., but the mean force was nearly constant between NE. and SE. The mean force with which the wind blew be- tween NNE. and SSE. = 0°52 Ib., between NNW. and SSW. = 0-78 Ib., or in the ratio of 2 to 3. When the projection of the previous values upon the directional midi are connected, a very symmetrical figure is formed, having three minima at intervals of about 80°, namely, at NE., NW by N., and WSW. (See curve c in the figure, p. ci.) Motions or DIFFERENT CURRENTS OF AIR. 216. Difference of the Directions of Motion of the Upper and Lower Currents of Air.—The mode in which the directions of motion of the clouds were observed is described in the introductions to the previous volumes in the section, ‘‘ State of the Sky.’? The process by which the results for the differences of motion of the dif- ferent currents were obtained by the combination of simultaneous observations, will be found stated in the volume for 1844, p. 440. The detailed results for each of the four years 1843-6 are given in separate tables in the present and in the previous volumes. The total number of comparisons of the currents of scud, cirro-stratus, and cirrus, with the surface-current, and of the cirro-stratous and cirrous-currents with the scud-current, was in 1843, 865 ; the numbers of results (each of from five to two comparisons) were in 1844, 995 ; in 1845, 964; and in 1846, 541. In the discussion for 1843 only one or two simultaneous observations were termed a com- parison ; from five to two simultaneous observations were termed a result for the three following years (see 1844, p- 440) ; but as the values of the final results for each year were not considered greatly different, the numbers of comparisons of 1848, diminished by a tenth, have received the weight of the results in the following years, and the numbers of results for 1846 were increased by a half in the combinations given below. The weights of the four years 18438, 1844, 1845, and 1846, were taken on the whole, therefore, as 779 : 995 : 964: 811. 217. The scud-ecurrent includes the cumulus ; the eirro-stratous current includes also the cloud termed in the Makerstoum Observations the cirro-cumulo-stratus : this cloud, so frequently seen, has received no name in Mr Howarn’s classification ; it belongs to the region of the cirro-strati, and is composed of great numbers of clouds like small cirro- -strati, arranged with a cirro-cumulous disposition. After this name had been applied to this cloud for some time, I discovered that Mr Howarp had given it already to the Nimbus. The cirrous current includes the cirro-cumulus. The order of reckoning being from north, by the east, south, and west, one current is considered positive of another when it proceeds from a point more southerly in the eastern semi- circle and more northerly in the western semi-circle. 218. When we consider the results for each quadrant, we find they present differences, both in the values and signs of the mean differences of the directions of motion; in three of the quadrants, however, namely E to S to W., and W to N., the signs are the same ; in every case the mean upper currents proceed from points positive of the currents below them. In the quadrant S to W. by far the greatest number of results have — been obtained, and they are by far the most regular and distinct. Thus, in 774 results, each obtained from several comparisons of the current of seud with the surface-wind, 664 shewed the seud-current to proceed from a point j | MorTIONS OF DIFFERENT CURRENTS OF AIR. clil 24° more northerly than the surface wind; while there were only 58 results shewing a more southerly motion, and 19 in which both currents proceeded from the same point. It might be supposed that the regular differ- ence of these currents was due to some peculiar configuration of the surface of the country around the Obser- vatory, but this is disproved by the results of the comparison of the upper currents with each other ; thus, the cirro-stratous current, compared with the scud-current, shews on the average of 255 results that the upper current proceeds from a point 14° more northerly than the lower current: a similar result is obtained from a comparison of the cirrous current with the scud-current. TABLE 97.—Differences of the Directions of Motions of the Lower and Upper Currents of Air, as deduced from the Comparisons of the Direction of the Wind, and the Motions of the Clouds, for the Years 1843-6. Quadrant N. to H. Quadrant E. to S. Quadrant 8S. to W. Quadrant W. to N. Currents. Mean Mean Mean Mean No. Mean INO} Ofe |e Mea No. , No. of |_. ) meee Diffs. of ae Results. Diffs. of Resale eerie Diffs. of nee Results. Diffs. of poh Motion. Motion. Motion. Motion. : 297 | +93 76 | +24 664 | +24 166 | +20 Scud minus Tle Ose Nenera OG == 93 eT gel) (5e 9/213) |Zat90) | P5791) i798: 1-42" Wind. 12 0 9 0 19 0 15 0 : ; 64 | +40 AGh | 34 8718 || +40 103s) 4597 Cir-str. minus||| 46 | 51] +421 11 | -25| +20] 43 | -19| +33) 38 | -35| 411 Wind. 3 0 1 0 12 0 6 0 é f 50 | +36 Ae ot 190 | +27 107i le226 Pees minus 55 | 37.) = || 111 =26/ + 9 61° |--18| +14] 79 | -33:| + 1 Seud. 16 0 15 0 34 0 27 0 i : 20 | +58 15 | +60 190 | +45 Si, P8380 Cirrus minus 16 | -—59| +6 0 See Ovjullt £26) ail 23e lu SG mL: Wi —40y be 15 Wind. NOs. \aieO 1 0 10 0 7 0 ; ; 20 | +35 13a 54: 107 |°-E36 Slee 07, Cirrus minus Wp eee | es Ome SAG Cull es aw G yee ll 39.) 1 = aut: se, Seud. 2 0 1 0 12 0 13 0 219. It happens frequently that comparisons of the motions of two currents are obtained when the others do not exist, or are not evident from the absence of clouds within them or from the masses of clouds in the lower current ; it is for this reason that the comparison of motions above, obtained from observations partly simul- taneous and partly not, are to a considerable extent independent of each other ; yet it will be seen that they in general confirm each other. Thus, the differences of the mean results for the first two comparisons (in Table 97) should give the difference for the third; so in the quadrant S. to W. we have 33°—20°= +13° ; and the partly independent comparisons for the cirro-stratous minus the scud-current, give + 14°; and as the differ- ences of the first and fourth comparisons should give the fifth (in Table 97), we have 36°—20°= + 16°; and the partly independent comparisons for the cirrus minus scud, give + 20°. We obtain similar results in the quadrants K. to S. and W. to N., but the differences of the motions are less marked. This appears to be due chiefly to the greater proportion of negative results in these two quadrants. The means for the positive results do not differ greatly in any of the quadrants. In the quadrant N. to E. we find all the three cloud-currents positive of the surface-current, but only to the extent of 2° in the case of the cirro-stratous current; while the cirro-stratous and cirrous currents appear on the whole 1° or 2° negative of the scud-current. These differences appear due to causes belonging chiefly to the sudden appearances of the north-east winds, which are chiefly sur- face-winds, and are nearly or altogether unconnected with the upper currents. 220. When we combine the results in the four quadrants for each class of comparisons, we have the fol- } lowing means :— | Seud-current minus surface-current, mean of 1434 results, = +14°5 Cirro-stratous current minus surface-current, mean of 754 results, = +22°8 Cirrous current minus surface-current, mean of 349 results, = +29°6 Cirro-stratous current minus scud-current, mean of 683 results, = + 6°9 Cirrous current minus scud-current, mean of 3839 results, = +13°7 MAG. AND MET. ops. 1845 anp 1846. 2c Civ GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. It appears, then, that if we take the mean direction of the surface-current as W. 21° S., the directions of the four currents will be nearly as follow :— Resultant direction of the surface-wind (No. 207), W. 21°S. saleteieheicielellsusisioneilelachericasieisnes scud-current, Mie Vitise seseseeeee Clrro-stratous current, Wil a2: - cirrous current, Wi. 92 N, The mean resultant direction for the three cloud-currents, giving each an equal value, is W. 1° N. The mean resultant direction of all the currents, giving each an equal value, is W. 4° S. 221. If we neglect the distinctions of the upper currents, and consider merely the differences of all the results for the cloud-currents compared with the surface-wind, we obtain the following numbers :— Quadrant N. to E., 499 results, mean upper current minus surface-current, = + 5°8 wee eee eee 1 OL OS mM O76 Mee en aon Sa PRE nae oe ee ot OPT see teens Seto: Was S980, Lael Mana tn nmrne Een On cri 1 oot, cai eee e een epee eee ORO veeeee ees a ome ee 2O RnAERRaRt rian 5c 56 Sc CORB aS ERA REERERMAontnaceoossas ax oe LONG The mean upper current, therefore, is least positive of the surface-current in the quadrant N. to E., and it is most positive in the quadrant 8. to W.; the mean result for each couple of opposite quadrants is nearly the same, namely, 15° and 16°. 222. If we compare in a similar manner the mean cirro-stratous and cirrous current with the scud-cur- rent in each quadrant, we have,— Quadrant N. to E., 157 results, mean cirro-stratous and cirrous current minus scud-current, —=— 1°2 Nenerstalciee Hh. 60.8250), BG ee adh duces te ca caddon neaeeMaaatee een Ceaea seus ce necledeais genet ees Sanaa a eae ae caanae Be GO Wey ABT. cane t ogee tales gs can Gah nea eeppmeben ion so ocs's cre ceceiaee sce ieee ae eee aie ea cessed We GO Nis BAO eS spesiee acne Spates se ein oi ela opiate erica cternn' Soins v» «nisletic aera ete es ee ee a a In the quadrant N. to E. the mean of the two upper currents seems to differ nothing from the scud-current, and nearly the same seems to hold for the quadrant W. to N.; but in the southern quadrants the mean upper cur- rent is positive of the scud-current 16°. 223. It appears, then, from the previous numbers, that the mean upper current always proceeds from a point positive of the direction of the swrface-current, and that the motion of the mean of the higher currents, compared with the motion of the scud-current, obeys the same law in the southern quadrants. These results are in accord- ance with the conclusions from the causes of the oblique motions of the aérial currents. Currents of air pro- ceeding northwards from more southerly positions retain a portion of the excess of eastward velocity of the places from which they start ; hence the south-easterly winds become more southerly, and the south winds become more south-westerly, as they proceed northwards ; the extent of the change of direction depending on the greater or less rapidity with which they lose their excess of eastward velocity and acquire that of the more northerly lati- tudes on which they move. This loss of eastward velocity will depend upon the proximity of the aérial stratum to the surface of the earth, and therefore the lower currents of air will lose more of their eastward velocity than the higher currents, and the upper current of southerly winds will become more westerly than the lower eur- rents. If, in considering the currents of air which proceed southwards from more northern latitudes, we re- member that the lower currents, from their proximity to the surface of the earth, acquire the greater eastward velocity of the lower latitudes more quickly than the upper currents, it will be evident that the lowest current from the north-west should become less northerly than the upper current, and that the lower current from the north should become less easterly than the upper current. This, it will be observed, agrees with the results previously obtained ; we find, however, in the northern quadrants, that the seud-current differs less from the surface-current than it does in the southern quadrants ; this, it is conceived, is due to the fact that this current is nearer the surface in the northern than in the southern quadrants : it may, however, be due also to the greater proximity of the origin of the currents. We find also that the mean upper currents differ little or nothing from the scud-current in the northern quadrants ; it is only necessary to examine the numbers in Table 97 to see that this is not due to the smallness of the differences of motions of these currents, but to the num- bers of positive and negative results being more nearly equal. It has been frequently observed that when the lower current of scud is from a north-easterly point the current of cirri is from a north-westerly point; these | currents could not have had the same origin, and therefore the explanation of the differences of motions given above cannot apply ; this difference of origin oceurs in all the quadrants, and diminishes the apparent effect of the variable velocity of the earth’s surface ; it occurs seldomest in the south-west quadrant. EXTENT OF Sky CLOUDED. cv EXTENT OF SKY CLOUDED. 224. The Mean Extent of Sky Clouded, from 8 years’ observations, = 6-98, totally clouded, being = 10-0. TABLE 98.—Monthly Means of the Estimated Extent of Clouded Sky, the whole Sky covered being 10, for the Years 1842-50. March, Se a ee NMTIORrOOWWHE Owkhounsnawiu 225. Annual Variation of the Extent of Clouded Sky.—In the mean of 8 years the sky was most clouded in July and least clouded in December ; the change from month to month is by no means regular ; on the whole, however, the extent of sky clouded is greatest for the 5 months April to August, and it is least in the 4 months September to December. The means for these groups of months are as follow :— Jan.—Mar.=6-94. April—August=7:29. Sept.—Dec.=6-63. The means for the meteorological quarters are,— Winter, Dec._Feb. = 6°68. Spring, Mar—May=7'14. Summer, June—Aug.=7:31. Autumn, Sept._Nov.=6-79 The least extent of sky clouded for any month in the 8 years occurred September 1843= 5-26. The greatest extent of sky clouded for any month in the 8 years occurred July 1846=8-71. The mean for the month of December in each year was less than the mean for the year; and the mean for the month of July in each year was greater than the mean for the year. 226. Variation of the extent of Clouded Sky, with the Moon’s Age.—It is well known that no heat has been detected in the moon-light even with the aid of the largest parabolic reflectors ; it was conceived possible, how- ever, that though no thermal indication could be obtained at the surface of the earth, yet there might be some found in the dissipation or formation of clouds in the upper regions of the atmosphere; the observations of the extent of clouded sky for 1848 were accordingly discussed for this purpose in the volume for that year, page 303: the result was very indefinite; it was remarked, however, that as no observations were made in that year between 9" p.m. and 5? a.m., the period when the moon’s heating effect must be greatest, little else could have been expected. In the volume for 1844, p. 443, the discussion was repeated ; from it the extent of clouded sky appeared on the whole greater about full moon than about new moon ;—thus, the daily mean for the 15 days about full moon = 7-05, whereas the daily mean for the 15 days about new moon = 7-14; and - the daily mean for the 7 days about full moon = 6-94, and about new moon = 7:24. The difference of these numbers is still very small, and it was remarked (1844, p. 443), on account of the irregularities introduced by the sun’s cloud-forming power, that it might be desirable to limit the investigation to the hours of the night ; this has been done for the years 1844 and 1845 in the present volume, Table XXXIX., page 66, where the extent of clouded sky is given for each day of the moon’s age and position in declination in each year, as de- | duced from the 6-hourly observations between 9" p.w. and 22 a.m. It will be seen from No. 229 that the variation of the extent of clouded sky in the mean of the year is small for these hours, which include the epoch evi GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. of the minimum in the diurnal variation ; they are also the night-hours during which the effect of the full moon must be greatest : upon the whole, this mode of determining the fact, from a short series of observations, seems open to the fewest objections. The following Table contains the means for groups of 3 or 4 days. TABLE 99.—Variations of the Extent of Clouded Sky for the Six Observation Hours 9" p.m. to 25 A.m., with reference to the Moon’s Age and Declination for the Years 1844-5. After Moon’s Moon Age. 1844, 1845. Mean. farthest 1844, 1845. Mean. North. d. d. d. d. 14—16 +0-16 +0-55 + 0-35 27— 1 + 0-63 — 0-37 +0-13 17—20 + 0-58 +0-59 + 0-58 2— 5 +0-21 — 0-56 —0-17 21— 24 — 0-33 —0-51 — 0-42 6— 8 — 0-03 — 0-14 — 0-08 25—28 — 0-33 — 0-51 — 0-42 9—12 — 0-28 —0-12 — 0-20 29— | — 0-29 —0-39 — 0-34 13—15 + 0-44 + 0-42 +0-43 2— 5 +0-22 — 0-62 — 0-20 16—19 — 0-23 — 0-06 —0-15 6— 9 + 0-51 + 0-02 + 0-26 20—22 — 0-85 +0-80 — 0-02 23—26 227. The values for each year indicate that the extent of sky clouded was greatest about full moon, and least about new moon ; this is shewn with greatest distinctness in the means for 1845. We obtain the same result if we take from Table XX XIX., p. 66, the means for the 15 days with full moon in the middle, and for 15 days with new moon in the middle; these are, for 1844, 6-72 and 6:37; for 1845, 7:10 and 6-23 respectively. the mean 15 days about full moon = 6-91 For the years 1844 and 1845, tae mean 15 days about new moon = 6°30. It may be a question still, how far error of estimating the extent of clouded sky in the presence and in the absence of the moon may enter into the production of this result. It is conceived that the effect of error in estimation must be nearly constant: in dark nights the extent of clouded sky was estimated by the space shew- ing clear stars; and it is not improbable that the extent of cloud might be rather over than under estimated during the absence of moon-light ; an error which could only have diminished the distinctness of the result obtained. Before we refer the result to the heating effect of the moon, there are other co-ordinate facts to be considered with reference to the motion of the atmosphere. (See No. 200.) We may inquire, however, how far it agrees with the heating effect of the sun, thus ;—the extent of clouded sky appears greatest in summer, and least in winter, it appears greatest near noon, and least near midnight; apparently, therefore, the heating effect is to increase the amount of cloud, and, by analogy, we should have the greatest amount of cloud about full moon.* * Since the previous investigation was performed, I have met with a passage in Sir JOHN HERSCHEL’S very excellent “ Outlines “ of Astronomy,” page 261, in which he supposes that the lunar heat is extinguished in the upper regions of the atmosphere ; and adds, “ Some probability is given to this by the tendency to disappearance of clouds under the full moon, a meteorological fact (for as such “ we think it fully entitled to rank) for which it is necessary to seek a cause, and for which no other rational explanation seems to offer.” He adds as a note to the parenthesis,—‘ From my own observation, made quite independently of any knowledge of such “ tendency having been observed by others. Humboldt, however, in his personal narrative, speaks of it as well known to the pilots “and seamen of Spanish America (H).”’ Sir JOHN’s observations were probably purely qualitative not quantitative. I have much difficulty in making any objection to the conclusions of so accurate an observer, at the same time if his observations were not of comparative measurement, I must point to the previous conclusions from two years’ estimations, and add my own qualitative observation for a considerable period, that the clouds are both formed and dissipated under the influence of full moon, and that they are chiefly cirro-cumuli, or of that kind whieh I have termed cirro-cumulo-stratus (See No. 217), noticed frequently during the existence of the aurora borealis as the growing and dissipating cloud. Whether the resultant is an excess or defect of cloud during full moon, as compared with other periods, I have no impression, and think it extremely difficult to have any. Sir JOHN refers, in an addendum, page xv. of his “* Outlines,” to what he conceives a fact confirmatory of his conclusion, thus :—* M. ARAGO has shown, from a comparison of rain registered, as having “ fallen during a long period, that a slight preponderance in respect of quantity falls near new moon over that which falls near the “ fall. This would be a natural and necessary consequence of the preponderance of cloudless sky about the full, and forms, therefore, “ part and parcel of the same meteorological fact.’ It will be seen, No. 235, that this result has also been obtained from the Makerstoun Observations, but it may still be a question whether it is confirmatory of Sir JoHN’s conclusion. When we compare the annual extent of sky clouded with the annual fall of rain, we do not find any direct connection; I do not know whether the diurnal EXTENT OF Sky CLOUDED. evil 228. Variation of the Extent of Clouded Sky with reference to the Moon’s Position in Declination.—The discussion has been performed for this argument also, and the resulting means are given Table XXXIX., p. 66; and for groups of days, in Table 99. The two years do not agree well. If the cloud depends upon the heating influence of the moon we should expect the greatest value for the most northerly position of the moon; the result, however, would only indicate the excess due to the higher positions of full moon over the lower positions, and as the latter occur in summer, the epoch of maximum cloud, the result becomes complicated with other causes of variation. From the mean of both years the numbers indicate an equal extent of sky clouded for the 14 days about the moon’s farthest northerly, and for the 14 days about its farthest southerly positions, When four periods, of seven days each, are considered, the extent of sky clouded is on the whole 0-20 less for the mean of the groups for which the moon is near the equator than for either the northerly or southerly groups. TABLE 100.—Diurnal Variation of the Estimated Extent of Clouded Sky, for each Astronomical Season and for the Year, deduced from the Observations of the Years 1843-6. Mak. ° Mak. Nov. Feb. May. Aug. Mean Mean Dec. March. | June. Sept. Year. Time. Time. Jan. April. July. Oct. h. m. Dials 12 15 O 15 |] +0-59 | +0-53 | +0-49 | +0-57 || +0-57 13 15 1 15 || +0-52 | +0-60 | +0-38 | +0-69 || +0-55 14 15 2 15 || +0-58 | +0:-56 | +0-20 | +0-41 | +0-45 15 15 3 15 || +0-64 | +0-63 | +0-26 | +0-28 || +0.44 16 15 4 15 || +0-55 | +0-31 | +0-03 | +0-28 || +0-30 17 15 5 15 || —0-09 | +0-29 | —0-06 | +0-18 || +0-08 18 15 6 15 || —0-38 | —0-04 | —0-15 | +0-01 || —0-14 19 15 7 15 || —0-57 | —0-33 | —0-15 | —0-31 || —0-34 20 15 8 15 || —0-40 | —0-57 | —0-34 | —0-90 || — 0-56 21 15 9 15 || —0-43 | —0-56 | —0-33 | —0-78 || —0-53 22 15 10 15 || —0-86 | —0-75 | —0-36 | —0-78 || —0-69 23 15 11 15 || —0-63 | —0-29 | —0-48 | —0-63 || —0-52 229. Diurnal Variation of the Extent of Clouded Sky,—The variations in Table 100 have been obtained from the detailed tables for each year in the manner already described for the other meteorological variations. The following are the epochs of the maxima and minima, and mean extent of clouded sky for each quarter and for the year :— Maximum. Mean. Minimum. Mean. Winter, Nov., Dec., Jan., 95 a.m.—3" p.m. 65 35™ a.m. 10h p.m. 55 25m p.m. Spring, Feb., March, April, 95 a.m—3 p.m. 65 10™ a.m. 10° p.m. 62 10™ p.m. Summer, May, June, July, 9 a.m. 5h 40™ a.m. 12pm. 42 35™ p.m. Autumn, Aug., Sept., Oct., 1} p.m. 35 55™ A.M. 82pm. 65 15™ p.m. Year, 112>15m a.m. 55 35m a.m. 102 15™ p.m. 55 35™ p.m. law of the amount of rain agrees with that of the extent of clouded sky. There is no doubt, however, that the way in which cloud is generated by the solar heat must be different from that in which it is generated by the lunar heat, the former is due chiefly to héating at the base of the atmosphere, the latter to heating in the upper region; in any case, however, it does not seem evident, from the above considerations, that the lunar heat should generate more cloud than it dissipates. I may remark, in addition to the above, that the relation of the amount of rain to the amount of cloud must be chiefly a relation to certain kinds of cloud; those formed and dissipated in moonshine are not rain-clouds at all. May it not be for this reason, the conversion of a certain portion of aqueous vapour into clouds which are not rain-clouds that the least rain falls at full moon, while at new moon the same aqueous vapour is probably deposited below as rain-cloud? The cirri, the highest of all clouds, are, I am per- suaded, clouds of crystallization ; are they the least frequent in moonlight? does the moon heat not tend to dissipate them, and to convert them into watery cirro-cumulo-stratus ? I am strongly of opinion that the effect of the lunar influences in the upper regions of our atmosphere is of much greater im- portance than might seem at all probable: previous investigations have shown that the laws of magnetic disturbance vary more with the positions and age of the moon than with any other argument, and this is especially obvious when we regard the diurnal oscilla- tions. It has also been shewn from the Makerstoun Observations for 8 years, that the frequency of the aurora borealis is greatest near full moon. Scattered throughout the Makerstoun Observations, there will be found frequent reference to remarkable opera- tions occurring in the upper regions of the air near full moon, chiefly among the cirrus, cirro-cumulus, and cirro-cumulo-stratus ; this frequency, it is believed, is not wholly due to the better opportunity of observing these processes by moonlight, although that may be partially the case. I have used throughout the term “ extent of clouded sky,” because although there is a considerable probability that during a large series of observations the extent of sky clouded will be a measure of the amount of cloud, yet this is not absolutely certain. MAG. AND MET. oBS. 1845 anp 1846. 2d evill GENERAL RESULTS OF THE MAKERSTOUN OBSERVATIONS. The maximum extent of clouded sky occurs earliest in summer, at 9 4.m., and latest in autumn, about 1" p.m. ; in the other two quarters, however, the value from 9? a.m. till 35 p.m. is nearly constant: the minimum occurs earliest in autumn, about 8 p.m., and latest in summer, near midnight. In the mean for the year the maxi- mum occurs near 115 a.m. and the minimum near 10" p.m. The morning mean value occurs earliest in autumn and latest in winter: the afternoon mean value occurs latest in autumn and earliest in summer. 230. The ranges of the Diurnal Variations of the Extent of Clouded Sky are as follow :— Winter= 1-51, Spring = 1:38, Summer=1-05, Autumn=1:59. Year=1:27. The diurnal range is therefore least in summer and greatest in autumn and winter. QUANTITY OF RAIN. TABLE 101.—Quantity of Rain fallen at Makerstoun, according to the Observatory Rain-Gauge, for each Month in the Years 1832-1849. 231. The quantities in Table 101, from July 1842 till December 1849, were obtained from the Observa- tory gauge, which has its funnel-mouth 8 inches above the soil; the quantities from January 1832 till June 1842 are the amounts of rain found in the garden gauge (63 feet above the soil), multiplied by factors, constant for each month, which express the ratios of the amounts of rain found in the Observatory gauge to those found in the garden gauge during 6 years; these ratios are as follow :— Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 1056 1:030° £1°029" M118) 9 1-071 1-076 070) 1-058) 1.078) 1-081) SL OG isi The amounts of rain, therefore, in Table 101 were either obtained directly from the Observatory gauge, or they are such as would have been obtained in that gauge. 232. The mean yearly amount of rain at Makerstoun by the Observatory gauge from 18 years’ obser- vations = 26-350 inches. 233. The least amount of rain for any of the 18 years was obtained in 1842, when it was 21:688 inches ; the amounts for 1835 and 1844 were little more. The greatest amount of rain occurred in 1846, being 37-854 inches. The least monthly fall of rain occurred January 1835, being only 0-04 inch. The greatest monthly fall of rain oecurred July 1846, being =7:124 inches. QUANTITY OF RAIN. c1x 234. Annual Variation of the Fall of Rain.—From the means for 18 years at the foot of Table 101, the greatest amount of rain fell in October, and the least fell in April, the daily average for the latter month being rather less than half that for the former. The amounts of rain for the months of 5 une, July, August, Septem- ber, and October, differ little, the average daily fall for these 5 months being 0-0894 inch. The daily means for the quarterly groups with the greatest range of values are as follow :— ; in. in. Winter, Nov., Dec., Jan., = 0:0673 Summer, June, July, Aug., = 0-0788 Spring, March, April, May, =0-0519 Autumn, Sept., Oct., Nov., = 0-0902 Year, = 0-07.22 235. Amount of Rain with reference to the Moon’s Age.—This discussion was given in the volume for 1844, p. 447. The result, as obtaimed from 6 years’ observations of the Observatory gauge, may be stated shortly thus :— The average daily fall of rain during the second and third quarters = 0-0654 inch. Jn RARER EDS bd Sb oc 0te.00c 0s dogg een ROpERES Saar titen fourth and first.......... =0°0750 inch. So that a greater amount of rain fell about new than about full moon. (See Foot-note to No. 227.) oe ‘a a i a a a i g i i 3 5 a a E a 5 5 : i - 2 1 a 4 rT - i] £ rah Fou SNE ATH NATO TABLES OF RESULTS FROM THE MAGNETIGAL OBSERVATIONS MADE AT THE OBSERVATORY OF GENERAL SIR T. M. BRISBANE, Barr., MAKERSTOUN. 1845 anp 1846. AND MET. oBs. 1845 anp 1846. bo RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE I.—Mean Westerly Declination for each Civil Week-Day and Week in 1845. June. July. : Oct. 25° 25° 25 25 25° ca fA [11-52]| 10-70 : 11-53 10-55 |. 11- -63 | 11-41 11-76 : . 11-43 11-34 : 11-31 13-28 c -43 | 10-99 : . [11-01] 13-52 : ; [11-33] : : 11-41 13-83 ; c 10-81 : 10-44 14-10 : j 11-96 : 10-07 . [13-61] 6 : 11-10 ; 08-40 | [10-64] 13-41 : : 10-85 “8: 10-79 | 10-08 13-12 : 112: 11-04 ; 11:04 | 09-63 13-66 : : 12-02 : [10-27]| 10-28 14.84 é ; [11-17] . 10-50 | 09-91 13-18 : : 10-97 5 10-22 | 10-19 13-83 : : 11-16 : : 10-70 | 10-07 [13-61] . : 11-00 : 10-88 | [09-83] 13-48 : 4 11-07 75 : 11-53 13-18 : : 1-13 s 5 08-31 13-13 9. : é 11-28 13-02 : . [11-13] 13-25 : Efe -64 | 11-45 13-23 : : -20]| 11-32 [12-67] . : . 10-55 13-53 : . . 10-33 11-04 . . 12-47 11-96 . 10-93 12-33 : : [11-03] 11-69 ; . ; 11-01 12-33 . ‘ [11-04]| 10-97 [12-07] 9. 11-49 | 10-45 12-46 : 10-44. WOMNOUKWNWe TABLE Il.—Mean Variations of Westerly Declination, after Eliminating the Secular Change, with reference to the Moon’s Age, Declination, and Distance from the Earth, for 1845. Variations Variations|| After | Variations] After |Variations|] Before | Variations} Before | Variations of West | Moon’s | of West Moon of West Moon | of West and of West and of West Declina- | Age. | Declina- |/farthest| Declina- |farthest|} Declina- after | Declina- | after | Declina- tion. tion. North. tion. North. tion. ||Perigee.| tion. | Apogee. , ) , Day. ’ 0-41 0 0-45 14 0-56 0-27 0-57 15 0-00 : 16 0-61 : : 17 0-59 . 18 0-65 | 4: 19 0:83 6 6 20 0-43 43 21 0-10 : 22 0-43 : 23 0-43 “ 24 0-43 . 25 0-30 “ 26 0-36 ‘ 26 27 0-47 9 & IOULRWNeE De WO WwWRh OOD ATE 1] I] =I NOWPWN RE Pe NWR ODN 0-17 0-43 0-09 0-33 WW Om ee OW Ee to OI eososoosososoos NwWeW Ke NW Oe Oe AI Civil Day. Jan. 1 9-71 2 10-65 3 3-81 4 3-74 5 |l[ 5-57] 6 2-62 a 7-73 8 4-89 9 37-83 10 31-14 il 9-86 12 [18-78] 13 9-38 14 9-82 15 14-65 16 5-80 lz 6-76 18 6-92 19 || [13-70] 20 40-16 21 16-35 22 6-20 23 19-98 24 17:56 25 17-84 26 [19-81] Re 18-34 28 19-68 29 25-48 30 15-00 31 5:58 Feb. 6-68 [10-37] eho 11-70 15-54 14-84 13-11 — os No) i=) pt March. 14-08 [14-69] | 9-53 MAGNETIC DECLINATION, 1845. TABLE III.—Diurnal Range of Magnetic Declination for each Civil Day, as deduced from the Hourly Observations, with the Mean for each Week in 1845. April. May. June. July. Aug. Sept. Oct. Nov Dec 10-34 | 21-21 | [15-50]| 14-43 | 29-87 | 15.44 13-52 | 18-17 5-18 12-99 9-53 10-76 8-70 | 19-87 | 20-00 8-50 | [14-92]| 12-13 16-86 | 12-17 | 10-76 | 10-87 | [17-36]| 19-74 | 15-78 | 12-56 | 31-83 14-23 || [13-36]} 17-54 | 14-59 16-88 | 15-20 8-39 12-91 20-17 13-94 9-93 13-22 9-87 10-97 16-34 |[10-73]| 23-98 10-51 [14-34]} 13-19 | 13-39 | [12-59]} 13-03 13-65 11-62 4-87 8-80 13:89 | 14-14 16-46 15-06 11-42 |[14-50]} 10-59 16-27 |[ 9-51] 13-18 12-36 |[14-88]| 14-76 | 21-60 | 20-69 9-49 7-18 6:86 13-97 14-56 19-31 10-39 | 18-79 | 11-06 | 30-88 | [ 9-76] 3-79 12-34 | 11-17 | 15-76 | 14-69 | [14-65]| 10-05 | 26-76 | 13-95 6-95 14-95 | [13-22]} 11-16 13-86 11-63 16-42 9-21 9-18 5-28 15-35 14.41 14-03 9-38 11-44 | 13-36 | [14-94] 7-11 6-67 [22-48]] 12-71 12-28 | [12-70]| 13-03 | 14-90 6-31 4-15 | 32-87 67-37 | 14-14 | 15-86 | 12-52 9-37 | [16-02] 6-58 5-06 | [15-63] 15-11 17-26 | [12-56]} 13-60 | 19-75 7-58 9-89 4-63 27-56 9-77 18.44 12-83 12-15 15-49 | 13-89 9-22 |[11-48]} 12-79 10-10 11-20 9-24 | 15-14 | [14-86]} 30-00 | 20-70 | 25-30 8-61 18-30 | [15-81]| 11-14 | 13-99 | 18-52 | 27.22 | 13-16 | 21-02 | 15-49 17-56 19-31 14-16 16-15 13-36 | 18-84 | [19-52] 8-70 3-50 [14:58]| 15-76 15-21 | [14-14]} 12-65 13-29 | 22-61 6-82 8-21 13-44 | 12-91 18-42 11-03 14-78 | [15-47]| 36-57 6-33 |[ 7-60] 12-63 18-07 | [14-20]| 13-05 15-71 10-71 14-85 9.74 5-49 15-47 12-44 13-39 15-48 18-49 9-08 5-52 |[ 8-13] 6-73 15-11 14-38 | 13-88 12-02 j 0 5-63]| 13-71 11-69 | 10-47 6-20 18-34 |[11-91]| 10-17 | 26-07 | 16-15 | 29-96 | 13-26 8-44 4.22 14-90 8-19 | 11-92 | 11-00 | 16-77 | 11-74 |[ 9-69] 6-98 3-01 [16-51] 9-01 | 13-86 | [13-38]| 11-91 | 34-57 8-20 9-91 6:39 22:18 | 9-38 | 18-28 | 9-06 | 12-41 |[19-25]| 11-27 | 10-19 | [ 8-17] 14-39 | 10-87 | [13-08]; 10-90 | 37-11 11-12 8-23 | 10-56 4:07 14-16 | 14-40 | 11-29 | 11-23 | 22-00 | 14-60 7-70 |[13-30]| 16-99 28-70 13-55 | [21-12] 14-19 12-36 TABLE IV.—Means of the Diurnal Ranges of Magnetic Declination, with reference to the Moon’s Age and Declination, for 1845. Moon’s Age. WHONARNRwWNWH Of After Moon farthest. North. D CHOTA MNHRwWNHHE OF Day. After Moon Mean farthest | Range. North. d RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE V.—Hourly Means of Westerly Declination for each Month in 1845. Mean Time. March. FOUOANOuUb wor oOo — jl M. Jan, Feb. | March.| April. | May. | June. | July. | Aug. | Sept. Oct. Nov. Dee. | Year h , y , , ’ ’ , , , , ‘ ’ i} ’ 12 1:43 | 0-00 | 1-20 | 3-25 | 3-65 | 4.75 | 2.97 | 2-26 | 1-60 | 0-65 | 2-55 | 0-71 || 0-56 13 1-49 | 1-17.| 1-16 | 2-68 | 3-24 | 4.58 | 2-12 | 1-67 | 0-63 | 1-50 | 2-84 | 0-87 || 0-47 14 1.29 | 1-51} 2-15 | 0-70 | 3-71 | 4-15 | 1-74] 3-35 | 1-06 | 1-30 | 3-59 | 1:80) || 0:67 15 1-03 | 1-98 | 1-11 | 2:02 | 3-51 | 3-44 | 2-98 | 2-76 | 0-00 | 2-44 | 3.22] 1-96 || 0-68 16 2-25 | 1-66] 0-25 | 3-70 | 2-52] 1-85 | 1-91 | 1-06] 0-92 | 2-50 | 2-80 | 2-71 || 0:49 1g 2-79 | 1-20 | 1-37 | 2-22 | 1-36 | 0-58 | 0-80 | 0-35 | 0-65 | 2-93 | 2-68 | 1-86 | 0-04 18 3-79 | 1-84 | 1-23 | 1-49 | 0-28 | 0-00 | 0-33 | 0-00 | 1-73 | 3-08} 3-25 | 2.28 || 0-08 19 4-16 | 1-90 | 1-22] 0-29 | 0-00 | 0-45 | 0-00 | 0-83 | 1-55 | 2-48 | 3.13 | 2-29 |} 0.00 20 4.49 | 2-42 | 1-46 | 0-00] 1-90 | 1-46 | 1-19 | 2:10 | 3-22] 1-96 | 3-44 | 2-52 || 0-66 21 5-08 | 3-26 | 2-32] 1-68 | 3-89 | 3-78 | 2-95 | 3-86 | 4-20 | 2.82 | 4.48 | 2-37 || 1-87 22 5:89 | 4-23 | 3-72 | 4-85 | 7-14 | 6.99 | 5-09 | 6-24 | 6.26 | 5-34 | 5-88 | 3.49 | 3.90 23 6-35 | 6-25 | 6-37 | 8-38 | 10-12 |10-70 | 7-68 | 9-51 | 8-80 | 7-84 | 6-82} 4-98 || 6-29 0 6-69 | 7-15 | 9-04 | 11-60 | 11-87 | 12-36 | 10-00 | 11-82 |10-53 | 9-21 | 7-50 | 6-13 || 7-97 1 6-95 | 7-31 | 9-92 | 13-08 | 12-42 | 12-52 | 10-86 | 12-67 |10-02 | 9-42 | 7-49 | 6-43 | 8.40 2 5-89 | 6-21 | 9-14 | 12-05 | 11-63 | 12-15 | 10-31 111-55 | 8-42 | 8.33 | 6-79 | 5.30 || 7-45 3 5:34 | 4.20] 7-47 | 9-95 | 9-65 | 10-48 | 9-28 | 9-18 | 5.94] 6.54 | 5-47 | 4.62 || 5-82 4 4-85 | 3:76 | 5-10 | 8-36 | 7-97 | 8.88 | 7-87 | 7-02 | 3-74 | 4-61 | 4-36 | 3-10 |} 4.28 5 3:29 | 2-41 | 2-65 | 6-21 | 6-03 | 7-11 | 6-49 | 4.84 | 2-79 | 3-70} 3-33 | 1-85 || 2-70 6 3-28 | 0-68 | 1-63 | 4.50 | 5-14 | 6-17 | 5-12 | 2-37 | 1-31 | 3-75 | 3.34] 1-16 || 1-68 7 1-85 | 0-66 | 1-67 | 3-44} 4.86 | 5.98 | 4-76 | 3-06 | 1-29 |] 3-35 | 1-60 | 1.20 || 1.29 8 1-71 | 0-23 | 1-55 | 2-49 | 4-78 | 5-86 | 4-05 | 3-46 | 0-46 | 2-78 | 1-45 | 0-11 || 0-89 9 0-89 | 0-40 | 0-00 | 3-08 | 4.33 | 5-53 | 3-59 | 2-34 | 0-20 | 1-09 | 0-96 | 0-01 || 0.35 10 1-00 | 0-03 | 1.07 | 3-61 | 4-81 | 5-38 | 3-58 | 1-75 | 0-90 | 0-35 | 0-00 | 0-20 || 0-37 11 0:00 | 0-67 | 1-64 | 3-87 |] 4-41 | 4.93 | 3-03 | 2.24 | 0.32 | 0-00 |] 1-30] 0-00 |) 0-35 MAGNETIC DECLINATION, 1845. TABLE VII.—List of Seven Days in each Month of 1845 upon which the Magnetic Declination was least irregular. March. TABLE VIII.—Hourly Means of Magnetic Declination for the Seven Days least disturbed in each Month of 1845, corrected so that the Mean of each Seven Days equals the Monthly Mean. MAG. AND MET. oBS. 1845 anp 1846. 6 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE [X.—Variations of Magnetic Declination with reference to the Moon’s Hour-Angle for each Lunation, for the Six Summer and Seven Winter Lunations, and for the whole Thirteen Luna- tions of 1845. LUNATIONS. | Moon’s Hour- Angle. : 2d. 3d. 4th, . : A 5 . | LOth. h 0 1 2 3 4 5) 6 if 8 9 2-03 2-60 2-05 0-79 1-07 1-66 TABLE X.—Differences of the Hourly Means of Westerly Declination, as deduced from the whole Series, and the Seven-Day Series selected in each Month; or Table V. minus Table VIII. Jan. Feb. | March.| April. | May. | June. | July. | Aug. | Sept. Oct. Nov. | Dec. | Year. , , / , , , , ’ , i| : 12 ||—1-60|—1-30]—1-17|+0-01 |—1-53 | —0-48 | — 0-50 | — 1-32 | — 1-16 | — 1-97 | — 0-64 |— 0-98 | - 1.06 13 ||—1-19}—1-29 | —0-85 | — 0-92 | — 1-72 | — 0-93 | — 0-93 | — 1-24 | — 1-62 |—0-89 |—0-29 —1-11 | —1-08 14 ||—1-72}—0-88 |+ 0-54 |— 2-77 | — 1-02 |—0-61 | —0-74|}+0-05 | —0-59 | — 1-35 | +0-43 | — 0-42 | 0-76 15 ||—1-67|+0-05 | — 0.13 |—0-79 | — 0-80 |—0-14|+0-79} 0-00 |—0-62|—0-52 |—0-19 |—0-33 | — 0-36 16 |—0-58|+0-20 | —1-04/+1-32|—1-01 |— 0-36 |-+0-67 |— 1-05 | +0-03 | — 0-08 |— 0-43 |+.0-70 | —0-13 17 ||+0-09 | — 0-23 |+ 0-10 | + 0-87 | — 0-72 | — 0-30 | + 1-15 |— 0-16 |4+0-42|+0-51 | — 0-49 |— 0-28 | +0-08 18 |+1-25]+0-37]/+0-03 |+ 0-44 | — 0-66 | —0-12}+1-01 |4+0-39 |+1-98 |+.0-70 | +0-37 |+0-47 | +0-511- 19 |}+1-59/+0-29| 0-00|+0-64 |—0-16|+ 0-44 |}+ 0-43 }+ 1-45 |+ 1-65 |+ 0-66 |+0-56 | + 0-64 |+0.68 20 | +1-49|+0-56|+0-36 | +0-35 |+ 0-63 |+ 0-79 |+0-46 |+ 2-59 |+ 2-60 |+0-41 |+0-87 |+0-82 | + 1-00 21 |+1-40|+0-82 |+ 0-69 | + 0-78 | + 0-59 |+1-05 | + 0-37 |+ 1-75 |4+1-94]}+0-59 |+ 1-28 |4+.0-98 | + 1-02 22 | +1-25}4+ 0-73 |+0-91 |+0-79|+0-88 |+0-83 | +0-16 | +.0-37 | + 1-43 | +0-24|+0-90 |+ 1-06 | +0-79 23 |+0-61/+1-38}+ 1-07 |+ 0-46 | + 0-98 |+ 0-71 | — 0-25 | + 0-58 | + 0-79 | + 0-57 |+ 0-36 | +0-99 | + 0-68 O | 41-49 }4+ 1-53 }+ 1-18 |-+0-19 | +4 1-38 |4+ 0-24 | — 0-27 |+ 0-58 | +.0-77 |+0-56 | +0-95 | 41-01 | +0-80 + 1-50 |-+ 1-64) + 1-64 |+ 0-07 | 4+ 1-52 | + 0-20 | — 0-22 | + 0-66 | + 0-49 +0-76 | +1-10 +1-17) +0-88 +1-46|+ 1-33 | + 1-37 |+0-41 }4+ 1-89 |+ 0-16 }+0-51 |+0-55 | + 1-06 |+ 1-35 |+ 1-48 |+0-64 | + 1-01 + 1-04 }+0-55}+ 1-33 |+0-04]+ 1-23 | —0-40 |+0-63 | + 0-66 +0-72 + 1-03 |+ 1-10 |+ 1-12} +0-75 +- 1-07 |+0-96 | + 1-09 |+0-08 |+ 1-10 | — 0-02 | 40-29 |4-1-01 | — 0-06 | + 0-90 | + 0-28 |+ 0-70 |+0-62 1 2 3 4 5 — 0-08 |— 0-09 | — 0-36 |— 0-34 }+.0-37 | +0-28 | —0-45 |+ 0-78 | —0-26 |+ 0-09 | — 0-26 | —0-46 |— 0-07 6 uf 8 ’ ‘ ’ |-+0-18|}—1-42|—1-59 |—0-58 | 4+. 0-12 | —0-01 | — 0-68 | — 0-93 | — 1-27 |+ 0-78 |—0-08 |— 1-19 | — 0-56 — 1-20 |— 1-32|— 1-06 | —0-85 | —0-11 | — 0-19 | —0-42 | — 0-67 | — 1-28 | +. 0-87 | — 1-27 |— 0-92 || — 0-70 | — 1-07 |— 1-37 | — 0:80 |— 0-64 | — 0-53 | — 0-02 | — 0-89 | — 0-63 | — 2-33 | + 0-17 |— 1-22 |—1-39 | — 0-89 9 }—148 |-1-04|—1.72 |-0-24| — 1.09 |-0-31 |— 0-76 | = 1-85 | = 1-62 |= 1-37 | — 1.09 |- 0-87 | - 1-12 10 |—1-54|—0-84 | — 1.22 |40.08 | — 0-47 |—0-49 | —0-11 | — 2-32 | — 1-41 |— 1-84 | — 2-53 |— 0.93 | — 1-18 1 — 2:37 | —0-78 | — 0-44 | 4+-0-52 | — 0-82 | — 0-36 | — 0-34 | — 1-20 | — 1-68 | — 2-35 |— 1-23 |—1-32 | — 1-03 ~I | MAGNETIC DECLINATION, 1845. | TABLE XI.—Mean Difference of a Single Observation of the Magnetic Declination, from the Monthly Mean at the corresponding Hour, for each Civil Day and Week in 1845. April. May. TABLE XII.—Mean Difference of a Single Observation of the Magnetic Declination from the Monthly Mean at the corresponding Hour, with reference to the Moon’s Age and Declination, for 1845. After After Mean Moon’s Mean Moon Mean Moon Mean Difference.| Age. | Difference.|| farthest | Difference.| farthest Difference. North. North. . | D D 1-57 1-72 1-61 2:03 1-84 2-02 2-28 1-69 1-40 1-87 1-78 1-84 1-69 1-75 1-65 WONAMKRWNHR OF CONANHR WNW OE RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XIII.—Mean Difference of a Single Observation of the Magnetic Declination from the Monthly Mean at the corresponding Hour, for each Hour in each Month of 1845. | Mak: Jan. Feb. | March.| April. | May. | June. | July. | Aug. | Sept. Oct. Nov. | Dec. |} Year. 18 1-41 | 1-38 | 0-95 | 1-28 | 1-13 | 1-28 | 1-93 | 1-38 | 2-57 | 1-37 | 1-17 | 1-11 19 1-56 | 0-71 | 0-96 | 1-35 | 1-22 | 1-32 | 1-58 | 2:30 | 2-07 | 1-34} 1-69} 0-99 20 1-56 | 1-28 | 1-41 | 0-93 | 1-83 | 1-50 | 1-52 | 3-13 | 2-81 | 1-45 | 1-50 | 1-23 | 21 1-34 | 1-33 | 1-57 | 0-84 | 1-44 | 1-47 | 1-86 | 2-37 | 2-02 | 1-80 | 2-15 | 1-31 22 1-27 | 1-26 | 1-28 | 0-87 | 1-53 | 1-35 | 1-57 | 1-88 | 1-69 | 1-49 | 1-93 | 1-37 23 1-40 | 1-60 | 1-28 | 0-83 | 1-73 | 1-78 | 1-45 | 1-46 | 1-52 | 1-53 | 1-55 | 1-65 0 1-40 | 1-58 |] 1-24 | 1-34 | 1-77 | 1-40] 1-30] 1-46 | 1-48 | 1-47 | 1-97 | 1-80 1 1-81 | 1-89 | 1-39 | 1-48 | 2-02 | 1-54] 1-46 | 2-03 | 1-59 | 1-85 | 2-00 | 2-10 2 t1-77 | 1-47 | 1-46 | 1-52 | 2-22 | 1-47 | 1-30 | 1-94 | 1-53 | 1-96 | 2-04 | 1-88 3 1-55 | 2:34 | 1:37 | 1-60 | 1-75 | 1-70 | 1-38 | 1-94 | 1-87 | 1-81 | 1-82 | 2-02 4 1-20 | 1-67 | 1-24 | 1:37 | 1-71 | 1-42 |] 1-10 | 1-69 | 1-54 | 1-33 | 2-52] 1-58 3) 1-64 | 1-90 |} 1-70 | 1-16} 1-10 | 1-23 | 0-91 | 1-17 | 1-10 | 1-23 | 2-67 | 1-73 6 1-52 | 3-40 | 2-64 | 1-50 | 0-87 | 0-78 | 0-96 | 2-55 | 2-43 | 0-66 | 1-33 | 3-45 | if 2-46 | 3-02] 1:95 | 1-47 | 0-78 | 0-75 | 0:92 | 1:30 | 2:38 | 0-64 |} 2-38 | 1-53 8 1-96 | 2-52 | 1-64 | 2-20 | 0-92 | 0-60 | 1-02 | 0-89 | 2-50 | 0-82 | 1-48 | 2-39 9 2-79 | 2.46 | 3-25 | 1-60 | 1-22 | 0-70 | 1-36 | 2-57 | 2-65 | 2-36 | 1-67 | 1-94 10 2-62 | 1-59 | 2-55 | 1-21 | 0-88 | 0-79 | 0-68 ! 1-99 | 2-23 | 2-80 | 2-90 | 1-93 | 11 3-68 | 1-39 | 1-55 | 1-39 | 1-26 | 0-92 | 1-10 | 1-63 | 2-40; 3-20 | 1-84 | 1-7] | TABLE XIV.—Number of Positive and Negative Differences which occur between the limits of successive Minutes, for each Month, and for the Year 1845. Month. Jan. Feb. March — April May WRPWwWwWwaQ@waokhun 7, NWWWe NOH wD Pe June July Aug. TPR RWOWUNwWITH woe: NRNWUOUNWe DOR: = 3 i - _ a 5 Fi : 5 - 7 i — AAT DTINWDDMDODOOKRWNAWNHNE BOD AODOrnbRwwokwormee OWE Uw DWH e — OWE DN RK DWH Wee: DD We wwe por: w ew uw — mm bo eS) s COnw - 1042 “IO “WwW We MAGNETIC DECLINATION, 1845. TABLE XV.—Number of Positive and Negative Differences which occur between the limits of successive Minutes, for each Hour in 1845. | Makerstoun | s G a Mean Time. | 6’. 15/11 120%, | a | 4 3 1 1 | 12 4 3 6 2 : ee 3 ‘ae ee: | BG 5 : 3 | 17 ; : 18 “ ‘ 19 alone | 20 pa Wa 21 eet Nee Ah 4. bo bo 23 oe 0 — CNW D: bo i) aS PP wWwwrmry: (=) a a a a ea eet ae eee se ees ees eee ss eee eee eee ee eee eee eee _ ee e_eee_ua_ eee ee on + be pe AT: Dp wT {oe} © Ai nqnrawnwunw: —_ i) = eee eee ee ane ne ee ee MAG. AND MET. OBS. 1845 anp 1846. c 10 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XVI.—Number of Differences in 1000 (without reference to sign) which occur between the limits of successive Minutes, for each Month, and for the Year 1845. January February March April May June July August September October November December O NP ord 0 w : — : AND Pog . wT for) Year TABLE XVII.—Number of Differences in 1000 (without reference to sign) which occur between the limits of successive Minutes, for each Hour in 1845. Mak. 0’ s/ Mean to to Time. nbs 9’ ih 12 377 6 13 351 3 14 406 6 15 412 6 16 492 6 17 546 3 18 498 6 19 505 6 20 || 422 6 21 409 3 22 441 3 23 438 3 0 390 siete 1 361 3 2 399 32 3 . las 3 419 es 3 : 4 || 466 g 6 | 3 RP gerd). 5 Byte 6 6 : =k 5 eal eee 6 || 466 Spa G) ic- cea pes 7 447 3% ¢ 10 3 } Be wee cee 8 460 | 304. 34 & 5 6 3 558 : De dilmeses ee uae 9 358 ) ‘ ) ‘ 5 26 6 é a eres 33 10 399 3 } 3 13 300 . [> etl eee 5 1] 406 : Z ) 6 3 sce |, S37 Isso os ook ela Jan. Feb. March. | April. May. June. July. Aug. Sept. Oct. Nov Dec 0:00 0:00 0:00 0:00 0:00 0:00 0-00 0:00 0-00 0°00 0:00 0:00 1 4476 4890 4756 5030 4479 | [5555]| 5503 5999 4997 5167 5061 6035 ti 2 4831 | [4903] | [5031]| 5306 4827 5629 5638 5296 4423 5426 | [5548]| 6048 i 3 5184 5141 5158 5114 4882 5471 5607 | [5364]| 4876 5194 5456 6497 4 5307 5096 5352 5025 | [4927]} 5792 5897 4980 4759 5405 5407 3591 5 [5368]| 5193 5326 5034 5134 5593 5880 5107 5118 | [5492]} 5365 5053 6 6573 4385 5327 | [5144]} 5083 5748 | [5701]| 5120 5005 5610 5828 5412 . 7 5645 4984 5523 5249 5155 5809 5824 5383 | [5028]| 5618 5404 | [5359] 8 5669 | 4987 5279 5067 5429 | [5772]| 5677 5103 4739 5701 5782 5743 9 4095 | [4938] | [5248]| 5373 5468 5699 5320 5300 5127 5389 | [5841]| 6160 a 10 3605 5005 5030 5433 5436 6199 5477 | [5424]| 5422 4445 5996 6278 1 11 4970 5086 5005 5260 | [5520]| 5586 5438 5352 5372 5193 6023 6334 ) 12 [4686] |} 5179 5324 5506 5610 5100 5768 5341 5347 | [5330]| 6014 5996 | 13 4812 5366 5162 | [4625]| 5625 4999 | [5682]} 6063 5268 9695 6187 5106 | 14 5309 5314 5082 2008 5552 5449 5790 5886 | [5340]| 5663 6238 | [5707] ! 15 5327 5317 4957 4714 5460 | [5322]| 5880 0685 5218 5597 6311 5564 & 16 5166 | [5367] | [4981] | 4829 5432 5586 5739 5390 5501 5256 | [5841]| 5670 * 17 5383 5383 4833 4784 5449 5456 5771 | [5467]] 5334 5646 5460 5575 18 5230 5365 5113 5124 | [5320]| 5340 5566 4932 4763 5737 5309 5600 19 [4971]| 5456 4742 5019 | 4789 5744 5853 5390 4761 | [5316]| 5544 6065 20 3602 5904 4803 | [4831 5548 5853 | [5669]| 5517 4719 5762 5897 6289 21 5198 | 4718 4847 4332 5244. 5663 5373 5375 | [5243]| 4585 5912 | [6209] 22 5247 4663 4803 4567 0404 | [5774]} 5502 5806 5356 4908 5998 6486 23 5019 | [4762] | [4707]} 5158 0569 5719 5947 5516 5632 5412 | [6165] | 6506 24 4637 | 4312 4719 5407 5029 5760 5869 | [5543]| 6226 5396 5991 6306 25 4883 4479 4186 4960 | [5520]} 5905 4326 5670 4704 5144 6558 6481 26 [4955] | 4498 4886 5054 5470 5401 5109 0947 4556 | [5566]| 6632 6525 27 5039 4886 4416 | [4866]} 5715 5986 | [5221]| 4942 4700 5697 6579 6213 28 5033 4708 5004 4305 5933 5705 5222 5403 | [4869] |} 6052 5810 | [6163] 29 5121 4917 4452 5902 | [5691]| 5201 5842 4904 5695 5498 6244. 30 4542 [4971]] 5022 5638 5912 5601 4246 5183 6062 | [6068] | 5897 31 4557 5156 4900 5683 | [4964] 5940 5617 HORIZONTAL COMPONENT OF MAGNETIC Force, 1845. 11 TABLE XVIII.—Mean Values of the Variations of the Horizontal Component of Magnetic Force, the whole Horizontal Component being Unity, for each Civil Week-Day and Week of 1845. TABLE XIX.—Mean Variations of the Horizontal Component of Magnetic Force, after eliminat- ing the Secular Change, with reference to the Moon’s Age, Declination, and Distance from the Earth, for 1845. Variations of Hori- zontal Component. 0-00 0241 0256 0231 0164 0200 0214 0118 0230 0336 0217 0199 0431 0370 0409 0372 Variations of Hori- zontal Component. 0-00 0311 0239 0111 0265 0370 0135 0291 0246 0000 0260 0399 0367 0294. 0346 0350 After Moon farthest North. =) » = OC ONADUR WNW OH Variations of Hori- zontal Component. 0:00 0441 0381 0443 0209 0312 0249 0227 0150 0213 0286 0258 0391 0332 0331 After Moon farthes Variations of Hori- t zontal Component. Perigee. Variations of Hori- zontal Component. 0-00 0497 0503 0510 0329 0000 0310 0339 0394 0426 0370 0429 0496 0486 0464 =) & NOuUhwwoe MWe pow panss 0-00 0209 0321 0241 0315 6177 0289 0423 0482 0424 0167 0000 0227 0358 0311 0234 Before and after Apogee. -] S oy NOUR WNP PH wWOWHAUAaAN Variations of Hori- zontal Component. 12 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XX.—Diurnal Range of the Horizontal Component of Magnetic Force for each Civil Day, as deduced from the Hourly Observations, with the Mean for each Week in 1845. March. 0-0 0174 [0222] 0220 0136 0172 0193 0227 0269 [0232] 0315 0214 0172 0244 0346 0351 [0240] 0323 0447 0332 0668 0389 0307 [0488] 0559 0528 0475 0487 0274 0384 [0347] 0311 TABLE XXI.—Means of the Diurnal Ranges of the Horizontal Component of Magnetic Force. with reference to the Moon’s Age and Declination, for 1845. After After Moon Mean Moon Mean farthest] Range. |farthest} Range. North. North. i=) 00 3731 3281 3216 7364 4982 3286 3433 3301 3135 3422 2731 3276 3119 3194 0 1 2 3 4 5 6 7 8 9 10 HorizontaL CoMPONENT OF MAGNETIC Forces, 1845. 13 TABLE XXII.—Hourly Means of the Scale Readings of the Bifilar Magnetometer, corrected for Temperature, for each Month in 1845, Mean Time. Jan. Feb. | March.| April. | May. June. | July. Aug. Sept. Oct. Nov. Dec. Year. Gott. | Mak. h. h. Se. Div. | Se. Div. | Se. Diy. | Se. Div. | Sc. Div. | Sc. Div. | Se. Div. | Se. Div. | Sc. Div. | Se. Diy. | Sc. Div. | Se. Div. | Se. Div. 13 12 | 531-97|535-40|537-80| 535-40/ 539-33 | 542-27| 541-59 |541-57| 536-77) 539-26 | 541-97] 538-78 | 538-51} 14 13. || 531-27|534-91 |534-51 | 533-75 | 538-18 | 540-78 | 539-92| 539-37 |538-01| 540-23 | 542-76) 539-54 537-77] 15 14 ||526-11\533-87 | 532-13|526-60|537-21|539-95| 539-07 |537-89| 535-62) 539-81 | 542-87) 541-01) 536-01} 16 15 | 533-93) 533-95 |535-32|534-97| 537-07 539-57 | 538-84 | 538-85 | 536-65) 541-74| 543-99) 541-93 | 538-07} LIZ 16 ||535-94|535-63|533-77|533-65 | 536-85| 539-49 | 537-58 | 538-95 |536-96| 542-74| 544-91 | 543-86 | 538-36} 18 | 17 |537-67|536-03|536-24|535-38|535-54| 537-68 | 536-07 |537-22|538-12/542-07|545-64| 545-51 |538-60] 19 18 | 538-25|537-63 | 536-03 | 534-45 |534-76| 535-72) 535-00) 534-65 |535-81 541-46 | 546-32) 546.32 | 538-03} 20 19 |538-55/537-30|534-73|532-88 | 530-52) 532-90) 532-82/| 530-03 /530-13)540-21/ 544-91] 544-58 535-80] 21 | 20 |536-89|535-91|530-90|527-70|526-57| 529-20| 529-00|526-02|526-43 | 535-22) 540-36) 543-52 532-31) 22 21 || 536-46) 532-50|528-22|522-76 | 524-59| 526-90 | 526-68 | 523-63 |523-59| 530-66| 535-61) 541-06 || 529-39] 23 22 |534-06| 531-56|525-011520-52)|524-77| 525-94 | 526-04| 524-09 |521-87| 529-50| 535-74! 538-49 | 528-13} 23 |535-25|531-93|527-75 | 522-09 | 526-59| 529-37| 529-88 | 527-32| 526-60) 530-20] 535-34) 536-76 529.921 0 1535-72|533-43/531-71/525-44| 530-88] 535-78] 533-73 | 533-11 /531-47/ 532-61) 538-35 | 537-72) 533-33] 1 1537-44] 535-521533-96|530-97 |536-34| 540-03|538-20|539-80/537-02|537-59|540-99| 540-44 | 537-36} 2 |536-70|537-34|539-03|536-23 | 540-00| 543-74) 542-86 | 541-36] 538-58) 538-91 |542-10| 542-14) 539-91} 3 | 536-92] 538-76 | 540-26| 540-35 | 544-30) 546-29 | 546-43 | 546-13) 540-49) 540-77) 543-11 542-97 | 542.23] 4 |536-84|537-56|541-06|543-61| 548-14] 547-55| 548-13 | 547-30) 541-90|540-72/ 542-24 544-45 | 543-29} 5 536-94! 537-43 |540-32| 545-40) 549-39) 549-32) 549-89) 547-73 |543-10| 541-30] 543-64| 545.01 || 544-1} 6 ||536-80| 537-70| 540-37 | 546-13] 550-47 | 550-32/ 552-12) 547-21/545-31 | 542-82) 543-06|549-94|| 545-18} U 8 9 0 1 535-31|538-17|540-63|545-44|549-24| 550-64| 549-97| 548-39 | 543-89 | 542-91|542-25|546-16| 544-411 535-94| 537-82| 538-25 | 542-56| 546-57 | 548-64 | 549-39 | 545-73 | 540-40 | 542-43 |541-90| 539.68 | 542-444 536-04| 537-64 |540-11/541-40|544-59| 546-88] 545-80| 544-00/541-83 | 542-46|541-43| 540-22 /541-86} 533-37| 535-03 | 538-45 | 540-88 | 542-35| 545-34 543-12/543-46|539-66|540-61|541-70| 540-25, 543-19 536-35 | 538-67 | 539-69 |541-07| 543-26 543-18) 540-20 | 539-99! 541-70 940-18) : 14 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XXIV.—List of Ten Days in each Month of 1845 upon which the Horizontal Component of Magnetic Force was least disturbed. TABLE XXV.—Hourly Means of the Bifilar Magnetometer Scale Readings corrected for Tempera- ture, for the Ten Days least disturbed in each Month of 1845, corrected so that the Mean of each Ten Days equals the Monthly Mean. j Mak. | Jan, . | March. Se. Div. 38-06 36-21 35-80 36-30 SK SOOCANOUOKR WHY SCC — i HorizoNTAL COMPONENT OF MAGNETIC Force, 1845. 15 TABLE XXVI.—Mean Variations of the Horizontal Component of Magnetic Force, with reference | to the Moon’s Hour-Angle for each Lunation, for the Six Summer and Seven Winter Lunations, | and for the whole Thirteen Lunations of 1845. LUNATIONS. 8th. . | 10th. 12th. | 13th. Year. | 0:00 0:00 0:00 0-00 0-00 0490 0112 | 0209 | 0045 | 0364 |) 0155 | 0581 0244 0648 | 0379 || 0: 0263 t 0687 0326 1711 | 0402) 0: 0314 | 0868 0109 1000 | 0270] 04 0322 0721 0000 0134}0118]) 03: 0151 0778 0071 0088 | 0287 || 0: 0153 | 0654 0200 0171/0000!) 0; 0151 | 0641 0190 0125 | 0200 |) 0140 0461 0192 0000 | 0074 0056 | 0605 0599 0087 | 0164. |) 0000 | 0518 0654 0106 | 0175 0135 | 0634 0344 | 0280 | 0326 | 0018 0214 | 0864 0490 0322 | 0265 0251 | 0603 0280 0514 | 0266 0218 } 0580 0612 0452 | 0312 0277 | 0676 0647 0538 | 0284 0232 0500 0535 | 0: 0517 | 0214 0253 | 0218 0515 0507 | 0260 0188 | 0466 0419 0489 | 0248 0160 | 0260 0262 0566 | 0232 0141 | 0143 0325 0307 | 0206 0072 | 0041 0258 0465 | 0281 0125 | 0000 0451 0386 | 0097 0102 | 0283 } | 0070 0279 | 0294 0104 | 0470 0119 0384 0391 | i i lg oS March. | April. | May. g. | Sept. Oct. Se. Div. | Se. Div. | Se. Div. Se. Div. | Se. Div. | Sc. Div. — 0-26 |—3-74 |—1-00 : — 1-63 |— 1-80 —1-70|-—3-96|—1-61 : : —1-69|+0-50 — 3-67 | —9-93 |—1-90 : —2-10|}—0-35 — 0-98 |—0-25|—1-72 -40 |— 1-83 | +0-34 — 2.82 | — 2:02 |— 1-53 . -04 | —0-32| — 0-27 —0-75|—1-69|—0:-81 : —0-19}—0-81 —0-52|}—0-75|-—0-19 . —1-27)-0-18 —1-16/+0-53|—1-39 . . -05/—1-17|+0-11 —1-59/+0-18|—0-81 : -23 |—0-11 | —0-68 — 1-07 |— 0-28 |— 0-02 . 56 |-+0-29 | —0-49 — 1-33 }+1-28|}+0-26 . . : — 0-27 |+0-62 + 0-86 |+ 1-35 |+0-50 : + 0-77 | — 0-25 | +0-98]+ 1-31 |+0-44 83 |+1-15/+0-01 | +1-25/+1-49|+ 1-00 : : : +0-89/+ 1-13) + 3-01 ]/+0-86 |+ 0-43 : 72|—0-55 | +0-84 +1-95)|+ 2-27 |+ 0-26 : + 2-14 +0-46 + 2-29 |+3-62|+2-68 : -44/+1-68}+0-72 +2-00}+ 2-61 |+ 1-25 : + 0-36 — 0-19 | +1-76|)+2-32)+1-84 : : +1-59)+0-57 | —0-92 + 1-56 |+ 1-87 : 48 | 40-42 |+0-64 | — 1-30 +1-22|+0-85 . -03|}—1-78!+0-72 +1-21/}—0-36 : : +2-15;)—0-39 +0-81|—0-12 : : —0-21/}-1-01 +0-02}—0-01 + 1-67 | —0-28 Se ee ed KH COOnNoauhwnwoH © —a 16 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XXVIII.—Mean Difference of a Single Observation of the Bifilar Magnetometer from the Monthly Mean at the corresponding Hour, for each Civil Day and Week in 1845. | [4-13] | 3-12 5-90 2-43 TABLE XXIX.—Mean Difference of a Single Observation of the Bifilar Magnetometer from the Monthly Mean at the corresponding Hour, with reference to the Moon’s Age and Declination, for 1845. After After Mean Moon’s Mean Moon Mean Moon Mean Difference.| Age. | Difference. || farthest | Difference.| farthest | Difference. North. North. Ve Day. 14 15 0 1 2 3 4 5 6 7 8 9 10 HorIzoNTAL COMPONENT OF MAGNETIC Force, 1845. 1% TABLE XXX.—Mean Difference of a Single Observation of the Bifilar Magnetometer from the Monthly Mean at the corresponding Hour, for each Hour in each Month in 1845. Jan. | Feb. | March.}| April. | May. | June. | July. | Aug. | Sept. Oct. Nov. | Dec. Year. | h. Se. Div. | Sc. Div. | Se. Div. | Sc. Div. | Se. Diy. | Se. Div. | Sc. Div. | Se. Div. | Sc. Div. | Sc. Div. | Sc. Div. | Sc. Div. || Sc. Div. 12 5-82 | 4-31 3-59 | 8-02 | 3-91 2:04 | 2-53 | 3-40 | 5-72 | 5-62 | 2-52] 6.94 4-54 13 6-11 | 4-86 | 4-03 | 8-93 | 3-57 | 2:70 | 2-68} 3-60] 4-51 | 3-20 | 2-63 | 6-32 || 4-43 | (SU) iN tN to tN wT bo So (ee) 14 14-29 | 4-37 | 6-14 18-24 | 4:87 | 4:11 | 3-30 | 2-23 | 5-19 || 5-89 15 4-46 | 4:00 | 3-67 | 4:38 | 4-34 | 2-84 | 2-89 | 3-38 | 4.05 | 2.50 | 2-44] 4.48 || 3-62 16 4-31 | 3-05 | 5-29 | 5-14] 3-19 | 2-80 | 3-69 | 2-63 | 3-78 | 2.61 | 2-80 | 3-28 || 3-55 | NZ 3-50 | 3-63 | 3-27 | 3-90 | 3-55 | 2-07 | 2:65 | 3-42 | 4-48 | 3-03 | 2-46 | 3-87 || 3-32 18 2-63 | 2-93 | 2:42 | 3-61.) 3-81 | 2-27 | 2-92 | 3-77 | 4-89 | 3-30 | 2-94 | 3-24 || 3-23 | 19 2:95 | 3-10 | 3-10 | 3-38 | 4.62 | 2-60 | 2-81 | 4-35 | 5-48 | 1.99 | 4-17 | 3-04 || 3-47 20 3-19 | 3-28 | 3-58 | 3-42 | 4.41 | 3-00 | 3-46 | 5-22 | 5-58 | 3.43 | 3-49 | 3-30 3-78 | 4-38 18 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. 9 TABLE XXXI.—Mean Values of the Variations of the Vertical Component of Magnetic Force, the March. April. 0:00 0,00 5601 5468 [5555] 5401 5560 5517 5525 5492 5524 5475 5478 | [5481] 3487 5460 5525 5412 [5520] 5333 5525 5378 5569 5481 5536 5523 5528 | [5324] 5507 | 4848 5455 5325 [5472] 5387 5356 5431 5474 5458 5511 5245 5424 | [5368] 5418 5330 5322 5384 [5387] 5359 5391 5407 5282 5462 5488 5252 5438 | [5245] 5422 4966 5509 5142 [5457] | 5243 5502 May. June July. Aug Sept Oct. 0:00 0°00 6°00 0°00 0-00 0-00 4717 | [5100]) 4573 4771 4489 4493 5305 5082 4912 4369 4505 4326 5275 5090 4813 | [4626]| 4905 4475 [5262]| 5262 4883 4693 4842 4381 5425 5164 4737 4635 4744 | [4415] 5419 5061 [4746]} 4651 4843 4523 5432 | 5056 | 4685 | 4662 | [4698]| 4427 5462 | [5063] 4694 4525 4673 4361 5329 5019 4662 4654 4581 4262 5279 5011 4743 [4701]| 4504 4297 [5199] } 5066 4766 4812 4625 4478 5001 4980 4936 4760 4566 | [4283] 5057 4996 [4829] 4793 4543 4376 5069 4957 4897 4687 [4582] | 4155 5119 [5083] 4892 4800 4638 4131 5158 5171 4739 4887 4575 4267 5194. 5187 4732 | [4732]| 4548 4288 {[5149]} 5210 4648 4537 4168 4237 4905 4881 4620 4724 4345 [4237] 5318 4895 | [4728]| 4756 4543 4214 5202 4816 4764. 4737 [4422]| 4287 5227 | [4948]| 4759 4758 4474 4128 5162 5051 4845 4567 4584 4299 5219 4988 4918 | [4646]| 4418 4414 [5226]| 5055 4249 4508 4301 4291 5259 4991 4681 4646 4340 [4504] 5274 4986 | [4675]| 4662 4435 4413 5218 5047 4715 4555 [4379]| 4236 5111 [4891] 4769 4326 4381 4174 5084. 4837 4716 4253 4322 4159 4970 4636 [4505 | 4278 Nov. Dec 0-00 0°00 4319 4264 [4398]| 4295 4330 5219 4535 4683 4766 4703 4436 4577 4264 | [4547] 4150 4535 [4294]| 4419 4359 4365 4195 4295 4360 4317 4423 4506 4398 | [4315] 4381 | 4315 [4379]| 4213 4405 | 4247 4392 | 4333 4273 | 4322 4200 | 4256 4326 | [4249] 4408 | 4239 [4307] | 4187 4453 | 4155 4370 | 3974 4083 | 3919 3906 | 4029 3980 | [4011] 3967 | 4122 [4272]| 3975 4048 TABLE XXXII.—Mean Variations of the Vertical Component of Magnetic Force, after Eliminating the Secular Change, with reference to the Moon’s Age, Declination, and Distance from the Earth. for 1845. Variations Variations | After | Variations Moon’s || of Ver- | Moon’s | of Ver- Moon of Ver- Age. |/tical Com-| Age. | tical Com- | farthest | tical Com- ponent. ponent. | North. | ponent. Day. 0:00 Day. 0-00 Day. 0:00 15 0051 0 0052 0 0170 16 0069 1 0061 1 0106 N7/ 0044 2 0100 2 0128 18 0068 3 0104 3 0000 19 0109 4 0142 4 0065 20 0101 5 0135 5) 0123 21 0045 6 0144 6 0152 22 0077 u 0069 ¥/ 0134 23 0103 8 0037 8 O161 24 0069 9 0045 9 0158 25 0021 10 0089 10 0102 26 0034 tea 0069 ll 0166 27 0000 12 0003 12 0152 28 0029 13 0037 US 0160 29 0025 14 | 0053 After Moon farthest North. of Ver- tical Com- ponent. 6-00 0170 0132 0160 0237 0190 0186 0138 O198 | 0168 Variations || | Perigee. Before | Variations of Ver- tical Com- | ponent. and after Day. 0-00 7 0133 6 0129 5 O115 4 0117 3 0101 2 0159 1 0138 P 0130 1 | 0168 2 | 0243 35.1, 20193 4 | 0152 5 | 0166 6 0142 7 0063 | Before Variations and after | Apogee. of Ver- tical Com- ponent. VERTICAL COMPONENT OF MAGNETIC Force, 1845. 19 TABLE XXXIII.—Diurnal Range of the Vertical Component of Magnetic Force for each Civil Day, as deduced from the Hourly Observations, with the Mean for each Week in 1845. [1320] 1588 1720 2005 0736 0940 March. April. May. July. 0:00 0:00 0209 0343 0692 0240 0331 [0417] 0252 0444 0542 0336 0241 0189 [1429] 6551 0775 0483 0359 0727 0797 [0649] 1242 0467 0301 0721 1074 0342 [1136] 3602 0512 0564 0:00 4177 0190 0224 [0904] 0282 0256 0-00 1075 0405 0430 0313 0420 [0580] 0781 0873 0664 0609 0359 0458 [0390] 0269 0242 0406 0269 0248 Sept. 0:00 0945 0835 1783 0847 0775 0435 [0717] 1099 0642 0502 0451 0936 0520 [0534] 0373 0223 0700 2219 1017 0403 [0783] 0279 0397 0383 4499 0904 1659 [1449] 0577 0621 TABLE XXXIV.—Means of the Diurnal Ranges of the Vertical Component of Magnetic Force, with reference to the Moon’s Age and Declination, for 1845. After Moon’s Age. D WOANAUBWNHOE Moon farthest North. D WHONANHRwWHR OF Mean Range. 0:00 0532 0757 0642 1469 0741 1053 0792 0713 0822 0744 0973 0463 0544 0526 After Moon farthest 20 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. XXXV.—Hourly Means of the Micrometer Readings of the Balance Magnetometer, corrected for Temperature, for each Month, and for the Year 1845. Mean Time. Jan. Feb. | March.| April. | May. | June. | July. . Oct. Nov. Dec. Mie. Div.| Mie. Diy.| Mic. Div.| Mic. Div.] Mic. Div.| Mic. Div. | Mic. Div. Mic. Diy. | Mic. Div.} Mic. Div. |} 3 578-3 | 547-2| 529-8] 500-7| 507-5| 495-1] 464-2 416-8 | 422-8) 425-9 576-8 | 546-4| 524-4) 508-2] 498.6} 495-9! 462-9 414-7 | 422-0} 421-7 569-2! 545-8} 523-5! 507-0| 499-3] 497-9] 461-0 414-7) 418-1} 421-1 | 574-5 | 547-7| 520-1| 521-2] 497-3} 502-4] 461-3 -3| 416-:0| 418-8) 418-4 577-4| 548-4] 528-6) 519-2] 512.0| 507-6| 465-4 ‘8 | 418-2) 419-6} 419.7 578-6! 548-7| 534-7! 528-9| 519.8] 511-4] 467-6 . 419-3 | 420-3) 419-8 581-1| 548-6] 541-3| 537-5| 524.5| 514-5| 479.4 -2| 422.3} 420.2] 420.3 | 581-7 | 550-5| 545-6 | 541-6] 526-4] 515-0! 474-6 427-2} 422.0} 420.7 | 582-5| 552-7| 550-4| 544-1] 522.4) 513-9} 477.2 : 9| 431-5| 425-4) 429.5 582-2| 555-7] 550-5| 543-4] 517-0| 507-9| 474.0 432-5 | 426-5| 423-4 586-1| 557-7] 550-2} 541-0| 511-9| 500-4] 473-8 -7 | 429-3 | 425-6| 424.3 590-5 | 558-4] 545-6] 535-6] 508-2) 490-32] 468-9 : 430-2 | 428-9) 426-6 | 591-3| 561-4] 542.6) 531-1] 507-9| 486-6] 466-1 433-2 | 432-9 | 595-9| 566-4] 545-5] 534-8] 513-8] 489-7| 468-9 436-7 | 435-8 602.2) 572-4] 552-1] 541-6] 519-3} 493-8} 472.4 443-2} 440.9 | 607-9] 581-9] 560-1] 549-2} 528-8| 500-6] 479-0 447-4 | 445-5 609-1 | 583-5] 570-1] 551-9 -1| 509-4} 485-9 451-2| 447-7 610-7 | 587-0} 583-0] 555-5 -5| 513-4| 489.7 448-0 | 447-4 | 610-3] 583-2] 579-0| 558-8 -5| 514-3 | 490.3 ‘0 | 447-1 613-2| 576:2| 569-3| 556-6 512-4} 489-6 : 443-3 | 611-1] 572-8} 562-2) 549-9 510-3) 486-0 +2) 439-8 601-2} 566-3] 552-4) 543-8 5-4} 505-1} 479-3 -0| 433-7 582-5 | 563-2) 541-9] 535-8 -6| 499-4 | 474-8 428-9 555-2 471-0 March, : : g. E : Year. 0°00 . “0 ; 0-00 0097 2 0030 0043 | 0006 0000 | 0034 ‘ 0000 0019 | 0000 : ‘ : 0016 0026 | 0085 2 ‘ 0029 | 0146 0028 | 0212 0047 | 0255 0069 | 0303 0099 | 0304. 0119 | O30L 0126 | 0255 0156 | 0225 0206 | 0254 0266 | 0320 0361 | 0400 0377 | 0500 0412 | 0629 0374 | 0589 0304 | 0492 0270 | 0421 0205 | 0323 0174 | 0218 0094 | 0180 | | March. | April. Cy 2 =) ke oO o ON Aw we ONAKwhwore Jan. Feb. | March.| April. : Mie. Div. | Mic. Div. | Mic. Div.| Mic. Div. 12 588-3 | 559-8 | 542-7) 526-2 13 587-9 | 558-3] 543-6| 528-0 14 587-5} 556-2} 545-1] 531-8 15 586-3 | 556-8} 544-8 | 533-3 16 585-3 | 557-2} 545-0) 533-3 17 583-3 | 557-5 | 545-7 | 534-5 18 584:5| 556-6 | 546-3) 536-9 19 584-9 | 557-1 | 548-0} 542-1 20 586-3 | 557-8} 550-5) 545-1 21 585-3 | 557-9| 550-0) 543-9 22 587-8 | 559-4} 448-5] 541-5 23 589-5 | 559-1 | 544-0} 534-1 0 589-7 | 560-4} 540-8 | 527-6 1 593-4 | 561-7| 542-1] 529-8 2 596-6 | 564-9 | 545.7] 535-2 3 597-9| 569-3] 551-8] 538-7 4 598-0} 570-7 | 556-0| 540-3 5 595-7 | 569-8] 555-9! 541-1 6 595-2) 568-4| 553-8) 542-2 a 8 9 0 1 596-6} 566-4) 551-6] 542-9 595-8 | 565-6} 551-8) 540-1 595-4) 565-1] 548-1) 537-3 591-7 | 562-7] 545:7| 533-0 587-9 | 559-6 | 543-1 | 528-3 May. June ad | a. 2 2 3 3 5) 6 Gir a 9 12 13 13 May. 513-9 514-6 516-8 519-5 523-5 525-5 525-6 526-8 522-3 518-3 512-2 507-3 503-9 509-4 515-7 522-6 526-8 529-6 529-3 526-2 523-6 518-8 515-5 513-4 June. Mic. Dly.| Mic. Div, 496-6 497-4 499-9 505-2 510-6 014-6 517-8 517-6 517-0 510-3 501-9 491-7 488-7 491-3 494-9 498-9 504-6 506-4 507-7 506-5 505-5 502-0 498-4 495:8 Mie. Diy. 468-7 July. 468-5 468-4 470-2 472-0 476-2 478-1 479-9 477-6 477-5 473-3 473-0 466-3 462-5 463-2 466-3 473-6 480-0 483-4 484-3 482-8 480-4 476-1 472-8 VERTICAL COMPONENT OF MAGNETIC Force, 1845. 21 TABLE XXXVII.—List of Days in each Month of 1845 upon which the Vertical Component of Magnetic Force was least disturbed. Aug. Mie. Div. 454-4 454-4 456-5 459-0 463-2 466-1 469-7 473-1 470-0 470-2 4653 459-2 457-6 460-3 465:8 471-8 476-5 476-2 471-7 465-7 462-5 460-4 458-3 454-7 Sept. Mic. Div. 441-0 439-9 444-8 444-7 446-9 447-3 451-0 457-5 459-3 458-7 456-7 454-0 449-1 454-8 464-8 470-1 469-7 464.8 459-5 454-9 453-6 452.3 445-9 439-7 Oct. Mie. Diy. 421-0 422.0 423-5 423-1 423-2 422.5 423.2 426-8 429-0 430-6 428-6 428-4 428-9 431-9 438-0 444.5 448-9 447-4 443.7 440-2 436-2 431-4 428-1 423-1 Mice. Div. | 424-5 424-3 422.7 422.7 422-0 422-3 422-1 423-6 427-3 428-0 428-3 431-3 435-2 437-5 440.7 442-0 441-7 439-9 438-1 436-3 435-2 432-3 430-8 Nov. Mic. Div. 428-8 427-9 426-0 425-0 424.0 423-7 425-0 425-4 427-0 428-1 428-1 430-1 432-4 434-3 439-3 442-9 441-6 439-8 439-2 |) 437-2 435-2 432.3 432-2 428-3 429.3 | Aug Sept. Oct Nov Dec d. d. d. da. a. 7 6 1 4 1 li 1] 3 7 5) 12 15 6 8 6 13 16 7 10 8 14 20 8 12 9 16 22 sla [3 10 TABLE XXXVIII—Hourly Means of the Balance Magnetometer Micrometer Readings corrected for Temperature, for the least disturbed days in each Month of 1845, corrected so that the Mean of each Monthly Series equals the true Monthly Mean. 488-8 22 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XXXIX.—Mean Variations of the Vertical Component of Magnetic Force, with reference to the Moon’s Hour-Angle, for each Lunation, for the Six Summer and Seven Winter Lunations, and for the whole Thirteen Lunations of 1845. LUNATIONS. Ath. ; . | 8th. . | 10th. | 12th. 0-00 0-00 0:00 0-00 0°00 0198 0017 0048 0160 | 0048 0181 0054 0101 0212 | 0057 0117 0058 0162 0203 | 0051 0161 : 0055 | 0: 0173 0177 | 0047 || 0162 0061 0109 0072) 0048 0163 0960 0129 0071 | 0042 0176 0085 0178 0048 | 0036 | 0099 56 | 0105 0177 0044 | 0013 || 0060 0091 0177 0031/0018 0000 0061 0157 0000 | 0017 0148 0048 0243 0020 | 0020 || 0228 0036 0197 0016 | 0036 0271 0027 0166 0075 | 0034 0293 0073 0121 0085 | 0049 || 0290 0078 0120 0071 | 0052 0320 0078 0129 0061 | 0045 0298 38 | 0056 2/0122 0085 | 0044 0212 0057 0131 0080 | 0024 0226 0050 10147 4 | 0078 | 0029 || 0240 0058 0114 0060 | 0011 |) 0233 0051 0093 0031 | 0008 || 0242 0040 0064 | 0025 | 0000 | 0294 0017 0054 0040 | 0005 0254 0000 0017 0037 | 0010 0225 0021 | 0000 0114 | 0016 || TABLE XL.—Differences between the Hourly Means of the Balance Micrometer Readings for the whole Series in each Month, and those for the selected Days; or Table XXXV. minus Table XX XVIII. | j ie Jan. Feb. | March,| April. | May. | June. | July. | Aug. | Sept. Oct. | Nov. Dec. Year. | | | | h. Mie. Div.| Mic. Div. | Mic. Div.} Mic. Div. | Mic. Div.| Mic. Div.} Mic. Div.) Mic. Div.| Mic. Div. | Mic. Diy.| Mic. Div.| Mic. Div. || Mic. Diy. 12 ||—10-0|—12-6|—12-9|—25.5|— 6-4] —1-5 |— 4.3/-—10-9/— 8-0] —4-2 | -1-7 |- 2-9])- 8.4 13 || —11-1|—11-9|—19-2}—19-8|—16-0/ —1-5 |— 5-5|—10-9}—18-4] —7-3 | —2-3 |— 6-2||—-10-9 14 | —18-3 |—10-4 |— 21-6 |— 24-8 |—17-5| —2-0 |— 9-2|—11-5/—18-3} —8-8 | —4-6 |— 4-9 |—-12-7 15 ||—-11-8|— 9-1}—24-7|—12-1 |— 22-2] —2.8 |—10-7|—14-2|—19-4| —7-1 | —3-9 |— 6-6) —12-0 16 ||\— 7-9|— 8-8|—16-4|—14-1|—11-5| —3-0 |—10-8|—-11-6]—17-1 oh eal 4-3)- 94 17 |- 4-7|- 9-0|-11-0]— 5-6/— 5-7] —3-2 |—10-5|— 7-9|—14.2] —3-2 | —-2.0 |— 3.9]- 6-7 18 |-— 3-4/-— 8-0/— 5.0|+ 0-6 1-1] —3-3 |— 7-5|-— 4.5]/- 9-8} -0-9 | -19 -— 47|/— 4.1 19 3-2|- 66/- 2-4)/-— 0-5|— 0-4} -2-6 |-— 3-:0|— 3-8|/— 7-5} +0-4 -1-6 |— 4-7 |- 3-0 20 |— 3-8|— 5-1/— 0-1/— 1-0/+ 0-1] —3-1 }— 0-3/— 1-0|/— 6.4] +25 | -1-9 |— 4:5||— 2.0 21 |— 3-1/— 2-2}+ 0-5/— 0-5/— 1:3) —2-4 |4 0-7|/— 2-3/— 4-2} 41-9 | —1-5 |— 47||— 1-6 22 |-— 1-7)/- 1-7/+ 1-7/- 0-5)/— 0-3} —1-5 |+ 0-8)/+ 0-5}- 1:0] +0-7 | —2-7 |- 3-8))- 0-8 23 |/+ 10]/— 0-7/+ 1-6/+ 1-5/+ 0-9} —1-4 |+ 2-6/+ 2-6/+ 0-8} +1-8 | —2-4 |— 3-5/4 0-4 O |+ 16/+ 1-0/+ 1-8/+ 3:5/+ 40] —2:1 [+ 3-6)+ 2-6/+ 64] +43 | —2:3 |— 2-64 1:8 1 |+ 25/+ 4-7/+ 3-4/4 5-0/4 4-4) —1-6 [+ 5:7/+ 4-:7/4+10-9) +4-8 | -1-7 |— 1:3]|4 3-4 2 |+ 56/+ 7-5|/+ 64/+ 6-4/+ 3-6) —1-1 |+ 6-1/+ 7-7/+12-3| +5-2 | +0-2 |+ 0-2/4 5:0 3 |+10-0/+12-6/+ 8-3)+10-5/+ 6-2) +1-7 |+ S4/+ 9-3/4+13-2) +2-9 | +3-5 [+ G14 76 4 | +11-1/+12-8|+14-1/+11-6/+ 7-3) +4-8 |+ 5-9/4+11-4/+16-1] 42-3 | +6-0 |+ 9-1)+ 93 5 | +15-0/4+17-2}4+27-1}4+14-4,/+10-9) +7-0 |+ 6:3)/+4+13-7)+24-4] 40-6 | +7-5 | 414-1 |+13-1 6 | +15-1 |+14-8}+25-2)4+16-6 411-2 +6-6 |+ 6-0/4+15-6}4+15-5| +0-3 | +9-0 |+14-6 +125 7 |4+16-6)+ 9-8 )4+17-7/4+13-7/4+ 9:3] +5:9 |+ 6:8)4+13-1)}4+15-1) +0-7 |} +7-0 |+ 12-3 + 10-7 8 | +15-3)+ 7-2/410-4)/4+ 9-8 + 8-0) +48 }+ 5-6)410-2/4+10-5) +2:0 +46 4 1:9 4 7-5 9 + 5:8]/+ 1-2/4 43/+ 65/+ 6-6/ 43-1 |+ 3:2/— 1-1/4 3-3] 44-6 | +14 |+ 26/5 Sa 10 |i— 9-2/+ 0-5/— 3-8/4 2-8)+ 6-1) 41-0 |+ 2-0)- 0-2/— 0-8} +41 -19 |-— 03) 00 11 |/-13-6]/- 4-4]- 5.0/4 0.3/4 4:3] —0-9 |+ 2:3/- 9-9|/— 2-1) —3-1 | -3-9 - 1:3)- 3:1 . VERTICAL COMPONENT OF MAGNETIC Force, 1845. 23 TABLE XLI.—Mean Difference of a Single Observation of the Balance Magnetometer from the Monthly Mean at the corresponding hour, for each Civil Day and Week in 1845. | Jan. Feb. March. | April. : : : : : Nov. | | Mie. Div. | Mic. Div. | Mic. Div. | Mic. Div. . ic. Div. | Mic. y. | Mic. Div. ic. Div. | Mic. Div. | Mic. Div. | Mic. Div. § 29-7 | 14-4 | 15-2 ; ; 20. 23. Aue tp) 83 24.6 | [19-0] | [12-2] 17-2 OONHD oP WH Ke | TABLE XLII.—Mean Difference of a Single Observation of the Balance Magnetometer from the | Monthly Mean at the corresponding hour, with reference to the Moon’s Age and Declination, : for 1845. After After Moon’s Mean Moon’s Mean Moon Mean Moon Mean Age. |Difference.| Age. |Difference.||farthest | Difference.| farthest | Difference. North. North. | Day. Mie. Diy. Day Mice. Div. Day. Mic. Div. i 15 13-3 Oi, | 17.6 0 17-2 , 16 14-5 1 17-8 1 11-4 17 15-8 2 15-3 2 14-5 18.4) teeembeews |) 13-5 3 29.6 ' 19 14-9 4 18-8 4 17-8 3 20 14.6 5 17-5 5 15-2 21 20-2 6 18-2 6 18-2 \ 22 14.7 7 14-0 7 13-3 4 23 16-0 8 19-8 8 13-4 24 18-3 9 14-5 9 18-5 25 20-0 10 12-4 . 11-3 26 15.4 11 12-8 . 13-8 27 17-9 12 22-2 . 13-3 28 21-0 13 15-5 ‘ 14-3 29 21-0 14 15-2 24 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XLIII.—Mean Difference of a Single Observation of the Balance Magnetometer from the . Monthly Mean at the corresponding hour, for each Hour in each Month in 1845. Feb. | March.| April. | May. | June. | July. . | Sept. h. | Mie. Div.| Mic. Div.| Mic. Div.| Mic. Div.| Mic. Div.| Mic. Div. | Mic. Div.| Mic. Div.| Mic. Div.| Mic. Div. | Mic. Div. | Mic. Div.|| Mic. Div.{ 12 25:3 | 26:5 | 23-4 | 49-4 | 22.5 9-2 | 14-1 | 24-3} 18-8 | 18-1 | 13-1 | 18-1 |) 21-9 13 23-3 | 24:3 | 30-1 | 36-1 | 35-9 9-5 | 16-0 | 24-5 | 25-7] 18-3} 14-1] 15-8 | 22-8 14. 36-3 | 22-6 | 31-5 | 44-2 | 36-8 9-7 | 20-8 | 25-5 | 25-0 | 19-1 | 17-7 | 15-2 || 25-4 15 30-3 | 19-5 | 32-8 | 25-9 | 42-1 | 10-0 | 23-3 | 28-2 | 28-8] 17-4 | 17-8] 16-8 || 24.4 16 26-5 | 18-2 | 24-0 | 31-5 | 27-7 | 10-6 | 22-1 | 25-1 | 27-8 | 15-8 | 16-5 | 16-1 || 21-8 | Vi 21-8 | 18-4 | 17-9 | 18-7 | 20-7 | 11-7 | 22-0 | 20-7 | 29-0] 13-9 | 16-3 | 17-8 || 19-1 | 18 19-7 | 17-7 | 11-2 | 10-9 | 16-7] 11-3 | 18-4 | 16-7 | 27-1] 12:5 | 16-9] 17-3} 16-4 | 19 18-3 | 15:1 84} 12-3 | 15-2 | 11-4 | 15-2 | 15-7 | 22-1) 11-6) 16-7 | 16-1 14-8 | 20 18-1 | 13-4 7-4 | 12-3 | 13-7 | 11-7 | 12-7 | 14-5 | 22-2 9-9 | 16-5 | 16-0 | 14.0 | 21 17-0 | 11-1 7-2 | 12-5 | 15-5 | 10-9 | 11-6 | 13-8} 18-1 | 10-9 | 15-4] 15-8 | 13-3 22 14-5 | 10-8 7-4 | 12-4 | 15-1 | 10-4 | 10-4 | 11-5 | 15-0 | 10-8 | 15-1 | 15-7 || 12-4 | 23 11-2 | 10-7 71 9-7 | 13-7 | 10-1 9-5 | 10-5 | 13-0 9-4] 13-4 | 15-4 11-1 | 0 11-4 | 10-7 7:5 9-3 | 13-8 9-2 9-8 | 10-4 | 13-3 | 10-1 | 12-4 | 15-7 11-2 1 11-8 | 10-9 7-7 | 11-6 | 13-9 | 10-0 9-4] 11-9 | 19-9 | 10-5 | 13-1 | 15-6 12-2 | 2 12-7 | 11-6 7-2 | 10-8 | 13-3 | 11-6] 11-1 |] 12-6 | 23-3 | 11-0] 14-8 | 16-5 13-0 3 14-9 | 15-8 8-8 | 15-0 | 13-2) 13-0 | 10-9 | 12-6 | 23-3 | 13-5 | 18-2 | 28-0} 15-6. 4 14.9 | 14:3 | 12-4 | 13-6 | 12-7 | 15-7 | 12-9] 16-6 | 21-8 | 17-1 | 20-9 | 31-8 || 17-1 5) 15-1 | 19-6 | 28-1 | 14-6] 13-4] 16-0 | 13-6 | 18-7 | 31-5 | 18-2 | 22:5 | 39-4 || 20-9 6 16-8 | 17-1 | 248 | 15-7 | 14:0] 14:8] 13-1 | 14-8 | 19-4 | 16-3 | 26-0 | 39-7 || 19-4 7 17-1. |: 10-5 |" 16-6 |. 12-9 | 14-3, |. 15-1 /).12:2"| 10-8: | 17-2. | 15:3: |. 23-0 235-60) 16-omn 8 | 16-5 9-7 | 12-6 9-3 9-1 | 13:9 | 10-5 7-1 | 14-5 | 13-9 | 19-9 | 21-6 || 13-2 Ooi) 15:5; |) Vega lide 6-6 7-8 |} 11-9 | 10-4 | 18-3 | 11-2 | 12-2 | 16-1 | 21-9 13-1 10 | 24:2) 14-3 | 14:2 | 11-1 7-9 | 10-9 9-8 | 13-5 | 16-0 | 10-5 | 13-4 | 18-4 || 13-7 1] 26-7 | 19-3 | 14-0 | 13-9 | 11-5 |-11-7 9-2 | 23-5 | 19-6 | 17-8 | 13-3 | 18-4 16-6 t VARIATIONS OF MAGnetic DIP. TABLE XLIV.—Variations of Magnetic Dip, with reference to the Moon’s Age, Declination, and Distance from the Earth, as deduced from Tables XIX. and XXXII. Variations Variations || After | Variations} After | Variations | Before Variations Before | Variations of ; of Moon of Moon of | and of and of Magnetic . | Magnetic |/farthest | Magnetic |farthest| Magnetic || after | Magnetic | after | Magnetic Dip. Dip. North. ip. North. Dip. ||Perigee| Dip. |Apogee.| Dip. os = — SSeS | Da S eo] r=) “ o o a 0-106 0-270 0-087 0-100 0-192 0-076 0-171 0-059 0-154 0-267 0-166 0-069 0-296 0-215 0-192 0-056 0-010 0-032 0-300 | 0-594. 0-267 0-187 0-191 | 0-171 0-128 0-259 0-104 0-228 2: 0-091 0-000 10: “16% 0-036 0-028 2 26 0-000 0-018 2 AY 3 0-056 0-052 0-215 0-219 0-219 0-313 0-318 0:295 0-337 0-254. i] | {| OCOONauRWNe © NOUR WN EMDR bw POO ATE NSIOUBP WN Pew PUD ATE | March. ne il 5 ial ty: 12 | 0-924} 0-310) 0-101 13 || 1-010] 0-373 | 0-524 0-861 0-380 0-479 0-713 1-320 1-712 2-176 1.729 1-121 0-824 0-154 0-059 0-046 0-288 ep) 0-240 7 0-800 | 0-209 | 0-100 8 0-687 | 0-225 | 0-373 9 0-569} 0-183 | 0-000 10 | 0-764 | 0-531 | 0-132 11 0-731] 0-255) 0-062 0.362 | 0-676 | MAG. AND MET. obs. 1845 anv 1846. 0-000 0-127 0-476 0-699 | 0-986 1-132 June, 1-039 | 1-261 1-264 1-406 | 1-508 1-574 1-876 2.194 | 2-610 3-138 3-410 July. | Aug. 0-625 1-491 | 0-945 1-595) 1-177 1-651 | 1-034 1-857 | 1-091 2-100; 1-411 2-306 | 1-858 2-646 | 2-573 3-230 0-000 0-323 0-435 VARIATIONS OF MAGNETIC Dip, 1845. 0-493 0-330 0-391 0-123 0-000 0-103 0-230 0-463 1-234 2-950} 1-909 3-213 | 2-044 | | 2-515| 1-951 1-813] 1-632 1-111) 0-942 1-003} 0-819 0-788 | 0-591 0-610} 0-638 0-470 | 0-520 0-000 | 0-259 0-155) 0-212 | | 0-602 0-254 0-306 0-227 | i 0-512. 0-356 0-419 0-457 | Noy. TABLE XLV.—Diurnal Variations of the Magnetic Dip in 1845, as deduced from Tables XXIII. and XXXVI. Year. G 26 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XLVI.—Variations of Magnetic Dip, with reference to the Moon’s Hour-Angle, for 1845, as deduced from Tables XX VI. and XX XIX. Moon’s LUNATIONS. H LUNATIONS, ; LUNATIONS. Hour- i : Angle. Summer. | Winter. Beit Summer. | Winter. Year. || Summer. | Winter. 0-146 0-218 ° 0-292 0-234 0-248 |, 0-160 0-052 0-081 0-086 . Hl 0-421 0-203 0-292 } 0-297 0-035 0-066 0-000 . | 0-195 0-157 0-179 0-282 0-094 0-000 0-023 . f 0-118 0-128 0-111 | 0-263 0-118 0-119 0-212 . i 0-065 0-113 0-081 } : 0-310 0-181 0-115 0-195 : | 0-115 0-157 0-126 | 0-276 0-108 0-159 0-173 . l 0-089 0-073 0-068 | | 0-289 0-166 0-228 0-130 . H 0-136 0-118 0-115 _ 0-200 0-217 | 0-202 0-161 WO ow whe OF TABLE XLVII.—Variations of the Total Magnetic Force, with reference to the Moon’s Age, Declination, and Distance from the Harth, as deduced from Tables XIX. and XXXII. i Variations|| After | Variations) After | Variations | Before | Variations| Before | | Moon’s of Moon Moon of and of and } Age. : Total farthest . |farthest). Total _after-| Total after Force. Force. North. North. Force. |Perigee.| Force. Apogee. | 0°00 Dz 0046 0046 0068 0088 0133 0102 0126 0054 0094 0000 0173 0051 0034 0096 0006 0088 0144 0042 0067 0164 0005 0000 0122 0035 5 0036 z 0149 0028 0051 0:00 0038 0055 0030 0045 0085 0080 0020 0060 =] 2 < OCOWMBDNBMABWW O- 0-00 0182 0148 0174 0225 0148 0177 0137 0196 ~) ® a 0-00 Day. 0131 7 0139" 0118 0127 0099 0162 0157 0156 0184 0225 0163 0150 0176 0149 0071 WONANK WHE OZ NOUR WNR PRE NMOW RON NMOUPWN RE PRO wW POD VARIATIONS OF TOTAL MAGNETIC Forcg, 1845. 2 1 TABLE XLVIII.—Diurnal Variations of the Total Magnetic Force in 1845, as deduced from Tables XXIII. and XXXVI. March. 1 Sh f . | July. 0°00 H 0°0 H 0:00 0138 | 0070 | 017 29 | 0138 | 0043 | 2 0102 | 0000 | 73 | 02 0073 0016 2 3 | 0255 | 0072 | 0070 0091 0160 233 | 0089 0216 | 0263 | 0 0116 0236 | 025 2 | 0105 | 0224 | 0127 | 0209 | 0073 0186 | 0271 | 0050 | 0122 | 0011 0137 2 4. 0000 0135 0011 0165 o9 | 0042 0224 é 0131 0356 | Of 025 0445 4 0340 0547 ; 5) 433 | 0427 0652 7 | 4 | 0486 0617 : i 0524 0534 | 05 505 | 0486 0436 | 0446 0374 0334 0256 ) 5 0255 0225 | | 0222 RPOONDIANAWNHO —— TABLE. XLIX.—Variations of the Total Magnetic Force with reference to the Moon’s Hour-Angle. for. 1845, as deduced from Tables XX VI. and XXXIX.. LUNATIONS. LUNATIONS. NiNoon?s LUNATIONS. - Hour- "|| Summer. | Winter. 5 eH] . | Winter. H fngle: Summer. | Winter. Year. h. 0:00 0:00 H i 0 | A 0°00 “00 j h. 0:00 0°00 0:00 0 0062 0053 | 0016 } 16 0065 0098 0078 rf 0081 0076 0008 Hea hy) 0031 0095 0062 2 0076 0088 | 0012 } 18 0023 0089 0053 3 0087 0065 0064 } 19 0023 0061 0039 4 0073 0010 | 0084 | 20 0000 0041 0017 5 0069 0000 0079 p 21 0025 0030 0024 6 0061 0016 | 0095 Racal Mpa 0045 0031 0033 7 0044 0025 | 0090 } 23 0047 0010 0022 | 24 0045 0025 0029 28 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE L.—Ranges for each Civil Day of the Magnetic Declination, and of the Horizontal and Ver-. . tical Components of Magnetic Force, as deduced from all the Observations (Hourly, Term-Day, or Extra) made in 1845. Civil || Decli- | Hor. | Vert. || Decli- |. Hor.: | Vert. || Decli- | Hor. | Vert.-|| Decli- | Hor. | Vert.. || Decli- | Hor. | Vert.:|/ Decli- | Hor. Day. | nation.| Comp. | Comp. |/ nation.| Comp. | Comp. |) nation.| Comp. | Comp. || nation.| Comp. | Comp. || nation. | Comp. | Comp. || nation.| Comp. ’ 0-0 0-0 4 0-0 0-0 4 0-0 0-0 ‘ 0-0 0-0 U 0:0 0-0 Y 0-0 | JANUARY. MARCH. May. JULY. SEPTEMBER. NovEMBER. ak 16°11 | 0322 | 0044 || 14°63 | 0251 | 0074 || 21:21 | 0602 | 0418 || 14:43 | 0435 | 0107 || 15:44 | 0476 | 0097 || 19:92| 0561 2 || 10°65 | 0151 | 0024 HEA See ee 9:53 | 0252 | 0019 | 8-70 0472 | 0040 || 26-46 | 0763 | 0083 ste ie 3 83:81 | 0081 | 0009 || 14-07 | 0451 | 0025 || 12°17 | 0358 | 0022 || 10-87 | 03854 | 0048 || 22-94 | 0487 | 0182 || 12°56) 0225 4 4:55 | 0073 | 0016 || 7-24 | 0199 |.0018 Bee Aa ... || 14:59 | 0368 | 0082 || 15:20 | 0889 | 0085 || 13:46} 0248 5 fai oF ane 6°58 | 0172 | 0025 || 9:93 | 0409 | 0028 || 9:87 | 0323 | 0042 || 16:34 | 0407 | 0077 || 34-39 | 0417 6 2-62 | 0095 | 0018 || 7-40 | 0193 | 0013 || 13°19 | 0400 | 0026 Aan sia aaa 13:65 | 0416 | 0043 4-87 | 0200 7 || 7:73 | 0225 | 0029 || 11:36 | 0227 | 0048 || 14:14 | 0448 | 0030 || 15-06 | G269 | 0081 an ane Bae 16°45 | 0358 8 5:35 | 0088 | 0015 9:06 | 0269 | 0031 || 12:36 | 0412 | 0085 || 14-76 | 0582 | 0098 || 20°75 | 0540 | 0110 718) 0161 9 || 64:96 | 2622 | 0570 Sere a ade 14°56 | 0447 | 0029 | 14:53 | 0368 | 0066 || 11:06 | 0468 | 0064 ee xe 10 || 32:09 | 2321 | 0133 || 12-20 | 0505 | 0055 || 11:17 | 0405 | 0030 || 14:69 | 0421 | 0061 || 10-21 | 0351 | 0050 || 18-24} 0175 nal 9°86 | 0193 | 00438 |} 14-30 | 0235 | 0026 See we ... |) 18°86 | 0451 | 0036 |]/.16°-42 | 0847. | 0045 9:87 | 0210 | 12 oe 28 at 7:48 | 0172 | 0022 || 14:41 | 0339 | 0045 || 9°38 | 0398 | 0046 || 13-86 | 0399 | 0094 7-11) 0171 13 || 10°21 | 0295 | 0041.|| 12-24 | 0244 | 0036 || 12-71 | 0427 | 0043 Bae ast a 14:90 | 0423 | 0052 4:15) 0153 14 || 10°56 | 0263 | 0037 || 20-99 | 0480 | 0072 || 14:14 | 0469 | 0100 || 12:52 | 0477 | 0027 Se Bae ae 5°06 0154 15 || 16-28 | 0449 | 0033 || 17-61_| 0351 .| 0067 || 17-26 | 0543 | 0124 || 13-60 | 0361 | 0024 || 7-58 | 0319 | 0037 4:°63| 0161 16 5°95: | 0126 | 0033 dis ph ae 18-44: | 0799 | 0082 || 12:15 | 0311 | 0041 || 13-89 | 0319 | 0023 a 650 17 11:53 | 0273 | 0027 || 16-96 | 0587 |.0092 || 11:20 | 0609. | 0045 || 15:17 | 0377 | 0027 || 35:27 | 0682 | 0107 || 30-61) 0692 18 6:92 | 0218. | 0014 | 16-66 | 9447 | 0069 oes Sie tse 13:99 | 0864 | 0025 |) 28:90 | 1182 | 0245 || 21:85) 0351 19 a ie ah 18-50 | 0414 | 0122 || 27-30.| 0885 | 0258 ||16-15 | 0392 | 0088 ||.20-72 | 0419, |:0102 || 12:30) 0217 20 || 42:00 | 1715 | 0479 || 23°48 | 0792 | 0382 || 15-76 | 0475 | 0035 oa age 20°39 | 0545 |: 0040 6-82 0141 | 21 || 21-50 | 0227 | 0049 || 17-65 | 0581 | 0100 || 12-91 | 0441 | 0066 ||11-03 | 0493 | 0029 |... | ... |... 0188 22 | 20-96 | 0819 | 0036 || 14-80 | 0322 | 0084 || 18-07 | 0493 | 008s || 13-05 | 0434 | 0049 | 10-71 | 0308 | 0028 | 12-94) 0368 > 09, oo 23 || 20°40 | 0493: |. 0066 LRU heck a MI RI Et 12°44'| 0386 | 0045 || 15-48 | 0462 |-0028 9-08 | 0364 | 0040 430 —s 24 21°38 | 0813 | 0181. || 31:15 | 0973: | 0343 |) 14:38 | 0573 | 0038 || 15:17 | 0552 | 0097 || 22°95 | 0496 | 0038 || 15-14) 0381 25 30°14 | 0785 | 0121 || 27-75 | 0715 | 0269 nas rab + {/,85°64 | 0788 | 0239 || 35:05 +] 1002. | 0461 8-44) 0210 26 Sirs age ats 25°63 | 0563 | 0137 8:19 | 0312 | 0020 || 11:00 | 0344 | 0080 || 11:74 | 0368 |, 0090 7:36 | 0316 27 =| 18:34 | 0479 | 0092 || 26-67 | 0934 | 0176 || 9-01 | 0337 | 0033 ae Wed ... || 3457 | 0668 |:0185 | 9-91) 01389 28 || 26°70 | 0664 | 0135 || 24:24 | 0326 | 0042 || 9°38 | 0321 | 0027 || 9-06 | 0389 | 0050 ae a8 ace 10°19 | 0571 29 || 29:95 | 0994 | 0193 || 20:94 | 0384 | 0082 || 10°87 | 0314 | 0036 || 10-90 | 0337 | 0029 || 11-12 | 0266 | 0058 |} 16°11 | 0392 + 3 24:67 | 0532 | 0065 ao Ans ee 16:99 | 0585 | 0053 || 11-23 | 0329 | 0044 || 14-60 | 0256 | 0062 . fon se — jp PRESSURE OF AQUEOUS VAPouR, 1845. 47 TABLE X.—Daily and Weekly Means of the Pressure of Aqueous Vapour, in inches of Mercury, for the Year 1845, as deduced from Tables I. and VII. March. | April. in. 0-175 aes beer -201 -170 -151 -162 -203 +230 TABLE XIJ.—Pressure of Aqueous Vapour, with reference to the Moon’s Age and Declination, for 1845. Mean Mean Pressure Pressure of k of Vapour. Vapour. in. . in. 0-273 0-282 277 271 271 +269 +257 °245 -270 278 275 +285 +282 284 277 270 +282 After Moon farthest North. D WONIAMNARWNWR OE Mean Pressure of Vapour. in. 0-249 +250 +254 -277 -271 -281 -289 -301 271 +278 +280 271 -278 -265 After Moon farthest Mean Pressure } of i Vapour. } in. 0-262 275 +261 -260 -268 275 -269 -262 -278 +268 +264 270 +262 -260 48 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XII.—Hourly Means of the Pressure of Aqueous Vapour for each Month in 1845, as deduced from Tables II. and VIII. March. 0-178 175 TABLE XIII.—Hourly Means of the Pressure of Aqueous Vapour for each Astronomical Quarter, and for the Year 1845. Feb. March, 0 1 2 3 4 5 6 7 8 9 0 1 —_— RELATIVE HUMIDITY OF THE AIR, 1845. 49 TABLE XIV.—Mean Relative Humidity of the Air for each Week-Day and Week in 1845, Saturation being = 1. March. 0-897 [ -873] -889 TABLE XV.—Mean Relative Humidity, Saturation being = 1, with reference to the Moon’s Age and Declination, for 1845. After Mean Mean Mean ‘Atoou Mean Relative Relative Relative Ganihaet Relative Humidity. | Humidity. Humidity. | yo,4,, | Humidity. | 0-835 } : 0-825 847 : 863 839 : 844 | -846 : 837 848 ‘ 848 839 : 855 842 ; 875 852 : 850 | 853 “8! 854 | 844 : 841 -829 s 844 843 : 824 845 j 847 849 : -840 863 50 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XVI—Hourly Means of the Relative Humidity of the Air for each Month in 1845, Saturation being = 1. BOONDYTHOMKRWNrHO — je TABLE XVII.—Hourly Means of the Relative Humidity for each Astronomical Quarter, and for the year 1845. | Feb. May. March. June. April. July. | 0-729 | 0-731 | 707 -720 704 -730 -706 “724 717 -739 ‘754 ‘799 ‘795 -785 841 -822 863 860 874 -888 ‘S91 “906 ‘897 -916 mSHOODNTIAUFPWNre O° — ATMOSPHERIC PREssuRE, 1845. ol TABLE XVIII.—Daily and Weekly Means of the Height of the Barometer, for 1845. Jan. March. } April. May. June. July. Aug. Sept. Oct. Nov. Dee. in. in. in. in. in. in. in. in. in. in. in. Dor sen 30-031 | 29-727 | 29-699 | 29-937 | 29-257 |[29-555]| 29-055 | 29-256 | 30-094 | 29-405 | 29-964 | 29-198 29-886 |[ 29-594] [29-770]) 29-889 | 29.383 | 29-559 | 29-411 | 29-230 | 30-066 | 29-439 |[29-815]| 29.288 29-614 | 29-788 | 29-642 | 29-791 | 29-469 | 29-153 | 29-468 |[29-336]| 30-057 | 29-322 | 30-103 | 29-037 29-741 | 29-922 | 29-789 | 29-857 |[29-502]} 29-049 | 29-588 | 29-323 | 30-062 | 29-320 | 29-881 | 29.253 | [29-798]| 29-677 | 29-957 | 29-908 | 29-682 | 29-105 | 29-950 | 29-496 | 30-044 |[29-343]| 29.502 | 28-870 | 29-691 | 29-783 | 30-166 |[29-537]) 29-638 | 29-038 |[29-626]| 29-506 | 30-090 | 29-641 | 29.271 | 29-026 29-964 | 29-873 | 30-185 | 29-628 | 29-585 | 29-462 | 29.688 | 29-463 [29-966]| 29-237 | 29-116 |[29-41 1]} 29-894 | 29-882 | 30-159 | 29-130 | 29-340 |[29-603]| 29-567 | 29-480 | 29.899 | 29-099 | 29.220 29-659 29-760 |[29-798]|[30-020]) 28-910 | 29.322 | 29-957 | 29-495 | 29-275 | 29.729 | 29-052 |[29.224] 29-689 | 29-370 | 29-421 | 30-035 | 29-030 | 29-408 | 30-047 | 29.415 |[29-535]) 29.970 | 29-122 | 29-193 29.969 | 29-230 | 29-826 | 29-848 | 29-406 |[29-610]| 30-008 | 29.458 | 29-497 | 29.931 | 29-286 | 29-195 | 29-631 [29-458]] 30-006 | 29-726 | 29-463 | 29.524 | 29-970 | 29-656 | 29-708 | 29.830 |[29-515]| 29-352 30-190 | 29-397 | 29-522 | 29-610 |[29-557]| 29.944 | 29-990 |[29.643]| 29-787 | 29-606 | 29-904 | 29-650 | 30-191 29-507 | 29-510 | 29-540 | 299208 | 30-123 | 29-957 | 29.695 | 29-663 |[29.475]| 29.972 | 29-767 [29-686]} 29.482 | 29-717 | 29-758 | 29-978 | 30-089 |[29-775]| 29-866 | 29-611 | 29-227 | 29.757 | 29.508 | 29.306 29-725 |[29-686]|[29-594]| 30-255 | 30-047 | 29-566 | 29.770 | 29-686 | 29-279 | 29.683 |[29-191]| 29-313 29-656 | 29-667 | 29-545 | 30-234 | 29.957 | 29-610 | 29.677 |[29-454]} 28-979 | 29.519 | 28.924 29-329 | 29-801 | 29-497 | 30-116 |[29-873]| 29-556 | 29.828 | 29-393 | 28-839 | 29.618 | 28-855 [29-622]| 29-899 | 29-617 | 30-053 | 29-705 | 29-683 | 29-952 | 29-244 | 29.297 |[29-742]| 28-441 28-632 | 29-370 | 29-789 | 29-941 |[29-988]| 29-746 | 29-899 |[29-871]| 29-126 | 29-573 | 29-546 | 28-580 | 28-583 29-857 | 29-573 | 29-993 | 29-972 | 29.693 | 29-829 | 29.976 | 29-571 |[29-516]| 29-973 | 29-101 (29-082) 29-798 | 29-285 | 29-769 | 29-854 | 29-717 |[29-713]| 29-935 | 29-804 | 29-505 | 30-116 | 29-341 | 28-839 29-410 |[29-566]|[29-760]| 29-702 | 29-744 | 29-841 | 29-857 | 29-597 | 29-970 | 30-139 |[29-237] 29.217 | 29-389 | 29-532 | 29-831 | 29-570 | 29-778 | 39.574 | 29-792 [29-650]} 29-912 | 29-939 | 29-804 | 29-835 29-353 | 29-755 | 29-643 | 29-430 |[29-751]| 29-450 | 29-682 | 29-505 | 29-396 | 29-983 | 29.452 | 29-845 [29-180]} 29-405 | 29-381 | 29-006 | 29-579 | 29-549 | 29-582 | 29-509 | 29-436 |[29-801]} 29-144 | 29-381 | 28-951 | 29-756 | 29-221 |[29-395]| 29-772 | 29-426 |[29-548]| 29-916 | 29-301 | 29-586 | 29-319 | 29.274 | 28-876 | 29-778 | 29-051 | 29-297 | 29-918 | 29-199 | 29-426 | 30-102 |[29-368]| 29-616 | 29-190 |[29-393] 29-101 29-782 | 29-558 | 29-796 |[29-347]| 29-464 | 30-127 | 29-421 | 29-546 | 29-199 | 29-347 29-036 [29-625]| 29-508 | 29-851 | 29-445 | 29-342 | 30-146 | 29-252 | 29-577 |[29-205]| 29-126 | 29-417 29-871 29-920 29-206 [30-099] 29-863 29-388 | 52 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XIX.—Diurnal Range of the Barometer for each Civil Week-Day and Week for 1845. Dep. Jan. Feb. March. | April. May. June. July. Aug. Sept. Oct. Nov. Dec. in. in. in. in. in. in. in. b in, in. | 0-053 | 0-249 | 0-130 | 0-076 | 0-066 | [0-229]) 0-706 | 0-061 | 0-123 | 0-161 | 0-092 | 0-396 313 |[ -268]|[ -193]| -067 | .265 | -198 | -581 -162 +333 -338 -181 -123 -565 -300 +332 *217 -057 177 |[ -147] 289 -540 -246] -219 -268 -070 -073 °245 +132 +524 -240 ‘087 -040 ‘051 :068 -400 +257 -200 +125. | -103 072 “119 “354 -152 |[ -195] +210 | 235 |[ -201]|[ -127]/ +140] -026 | -177| -076 OMIDNK Wd — h omcest | La) bo bo So jit} oS Ne) oO tN ww iw | sex | bo ww (<3) jet} TABLE XX.—Diurnal Range of the Barometer, with reference to the Moon’s Age and Declination, for 1845. , Mean : Mean After Mean After Mean see S|) Diurnal een S| Diurnal | heen t| Diurnal fumes Diurnal Be Range. BE: Range. pee Range. yactht Range. Day. in. Day in. Day. in. Day. in. 15 0-159 0 0-270 0 0-256 | 14 | 0-292 16 “190 1 +226 1 263 | 15 | +243 17 “261 2 +265 2 +210 16 +229 18 277 3 +218 3 226 | 217 -219 19 +285 4 +229 4 O71 | 18 261 20 -316 5 +240 3) -220 | 19 =) e%-232 21 337 6 227 6 267 | 20 | -182 22 +254 7 +275 U +221 21 | +203 23 309 8 +224 8 212) | 220 )|\* 231 24. +322 9 “174 9 “211 23 | +248 25 +149 10 ‘197 | 10 +246 24 +242 26 -270 11 “194 11 *203 25 +252 27 +234 12 +222 || 12 +208 26 314 28 +255 13 -150 | 13 +239 27 274 29 || -297 | 14 169 | | ATMOSPHERIC PRESSURE, 1845. 53 TABLE XXI.—Hourly Means of the Height of the Barometer for each Month, and the Year 1845. va Jan. Feb. | March.| April. | May. | June. | July. | Aug. | Sept. Oct. Nov. Dec. Year. h. | in. in, in. in. in. in. in. in, in. in. in. in. a 12 29.525 |29-693 |29-711 |29-648 29-695 |29-608 |29-623 |29-564 |29-660 |29.589 |29-329 |29-384 | 13 || -518| -690] -712| -641| -693; -604;) -619| -563] .657| -585| -319| -375|| 14 -518| -688| -710] -642) -691 600) -613] -564| -652| -583| -312 377 | 15 “511 ‘681 -706| -638| -689] -598} -612] -561| -647] -584] -301 372 | 16 504! -680| -709| -637| -690] -600| -613| -560} .644} 585] -.294 +366 | Nef “501 -681| -714| -640| -693| -603| -617| -566| -648) -586/] -293) -366| 18 -502| -683| -720| -646| -699| -603) -621 -570) -658| +593] +296} -368| 19 -508| -689| -731| -649; -701 606; -625| -575| .658| -603] -305| -371 20 519} -700| -740] -650| -704] -607!| -629| -577) -659!| -611 -317| .375 21 -526| -704| -747] +653) -703| -607| -629|) -580| .658| -613] -328| -381]) 22 -529| -708| -756) -653|) -702| -605| .630) -580|] -653| -615| -337! -388|| 23 -528| -716| -759| -651| -702) -602| .628|) -580! -647| -613| -338| -384]) 0 -524| -713| -761 648 | -700| -598| -627|) -580| -643] -608] -332) -378 || 1 || -514) -709| -756| -643| -700| -595/ .624| -580| -634| -601] -330|) -370 2 -509| -704] -753| -633| -699| -592) -622| -578| -628| -600| -328| -363 3 -510|} -704| -748| -627|} -697| -587| -616| -578| -624] -597| -328| -361 4 O11 -705| -748| -626| -696| +585) -612| -577| -624| -599| -331 -367 5 510) -711 ‘751 -628| -698| -584/ -612) -577| -630| -604| -334| -366 6 -510 716) -753|) -630} -705!| -586| -618| -580| -636| -609| -337)| -365 7 -509 | - -721 -759| -638| -713| +587) -622| -588} -641| -614| -336| -360 8 -510| -724| -760| -646| -722| -593] -626| -592| -646) -616] -337)| -354 9 -505| +724) -757| -645| -726| -592| -629| .597| -646|) -617| -334| -354 10 500) -726| -756] -647) -730| -592| -632] -599| -643| -615| -327| -355 11 -501| -725| -756] -647| -731 691 ‘633; +598) -640| -617| +322) -357 TABLE XXII.—Reduced Hourly Variations of the Height of the Barometer for each Astronomical Quarter, and for the Year 1845. > RP ODOONAMNKHWNrE OT — — MAG. AND MET. oss. 1845 anp 1846. ce) 54 TABLE XXIII.—Extreme Readings of the Barometer for each Month in 1845; Extreme Daily Heights for each Month; and Extreme Diurnal Ranges for each Month, together with the } Month. RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. Ranges and Means of the Extremes. Extreme Readings. Extreme Daily Means. Extreme Diurnal Ranges.§ TABLE XXIV.—Hourly Variations of the Pressure of Dry Air for each Astronomical Quarter, and for the Year 1845. | Feb. March. | April. in. 0-016 | ona | 004 000 002 005 009 .014 019 021 Highest. Lowest. Range.| Mean. Highest. Lowest. | Range. Mean. Greatest. | Least. 7 Qk, fine 3) ass a ant in. in. dein: an in. in. in. a) a | at (ee Jan 0 23 | 30-052) 27 18|28-809) 1-243 |29-430]) 1 | 30-031) 28 | 28-876) 1-155 | 29-453 || 25 |0-730, 7 |0-040 | Feb. | 11 22 |30-077| 25 17|29-213| 0-864 |29-645 || 12 | 30-006] 22 | 29-285) 0-721 | 29-645 || 24 |0-568 | 28 |0-031} | March) 8 23 | 30-244) 27 21 |28-839) 1-405 29-541) 7 | 30-185) 28 | 29-051) 1-134|29-618) 29 0-618 4 |0-057} April || 16 20 | 30-289) 9 4/28-860| 1-429 |29-574 || 16 | 30-255) 9 28-910) 1-345 |29.582)| 14 0-684 2 0-067§ May {13 BA 30-161 6 |29-225 | 0-936 |29-693 | 14 | 30-123] 1] Paved 0-866 |29-690 || 13 0-395 9 0-026} | June ue a 30-072) 3 11 /|28-874| 1-198 | 29-473 19 | 30-047) 6 29-038) 1-009 |29.542|) 3 |0-565 13 0.043] | July 5 10 |30-003| 1 5|28-727| 1-276 |29-365 || 21 | 29-976) 1 | 29-055) 0-921 |29-515|| 1 |0-706 ee 0-034 Aug. || 31 0 | 30-175| 19 20|29-008 | 1-167 |29-591 || 30 | 30-146] 20 | 29-126) 1-020 |29-636 | 21 |0-397) 13 \0-030} Sept. 0 13 | 30-162/18 2/|28-781| 1-381 |29-471]| 1 30-094 18 | 28-839) 1-255 | 29-466 || 19 0-721 4 0.032} } Oct. 22 9 |30-177| 8 16/28-946] 1-231 |29-561 || 23 | 30-139) 9 | 29-052) 1-087 /29-595 || 30 0-489 | 31 0-067} | Nov. || 2 13 |30-138/19 13 |28-239| 1.899 [29-188] 3 |30-103| 19 | 28.441 1.662|29.272] 20 |0-658| 3 |0-077] } Dec, | 12 11 | 30-284) 19 15 /28-282| 2.002 |29-283]/ 13 | 30-191] 20 28-583. 1-608 | 29-387 | 23 1147 15 0-134] | | PRESSURE OF THE WIND, 1845. 55 TABLE XXV.—Daily and Weekly Means of the Pressure of Wind, in Pounds on the Square Foot of Surface, deduced from the greatest pressures occurring between the Hourly Observations, in 1845. March. CO COE INI Cy) SOws Pe Cole bo) Se ee | WN) = 7S 14 a a o wo wow NH NY NY NH NY KF | = NOOO PP wWwnwnore © OO ONY bo bo Oo oO w i=) wo — 56 RtsuLts oF MAKERSTOUN OBSERVATIONS, 1845. TABLE XXVI.—Daily and Weekly Means of the Pressure of Wind in Pounds on the Square Foot of Surface, deduced from the greatest pressures observed within 10™ at the Observation Hours, in 1845. March. TABLE XXVII.—Mean Pressure of Wind with reference to the Moon’s Age and Declination, for 1845. TERESELLGU a RS) || ee LR IE Moon’s riers Mconts pera fe ae oe eres Age | wina, | “8 | wina. [res] wing, [SHS] wing. Day. 1b. Day. lb. Day. 1b Day. 1b 15 0:53 0 0-86 | 0 0-56 14 0-55 16 0-49 1 0-67 1 0-63 15 0-53 17 0-79 2 0-70 2 0-60 16 | 0-42 18 0-51 3 0-52 3 0-68 17 0-49 19 0-69 4 0-51 4 0-76 18 0-54 20 0-94 Bs) 0:38 5 0-34 19 0-59 21 0-49 6 0-42 6 0-51 20 0-50 22 0-55 a 0-55 | af 0-54 21 0-45 23 0-59 8 0-50 8 0-37 22 0-32 24. 0-57 9 0-48 9 0-50 23 0-65 25 0-48 10 0-44 || 10 0-51 24 0-55 26 0-59 11 O33 ew 0-44 25 0-82 27 0-68 12 0-48 || 12 0-58 26 0-92 28 0-70 | 13 0-40 || 13 0-75 | 27 | 0-69 29 0-66 14 0.39 I PRESSURE OF THE WIND, 1845. TABLE XXVIII.—Maximum Pressure of Wind in each Civil Day in 1845. oa Jan. | Feb. |March.| April. | May. | June. | July. | Aug. | Sept. | Oct. | Nov. | Dec. Ib. 1b. 1b. 1b. lb. lb. Tb. 1b. Ib. lb. lb. 1b. 1 Oslo) Ome etemeet 7a 6:20 1-5 °| 26.00) 4-1, |) 0-6) 3.5.) 0-4 | 5:0 2 Osten Oso -SaerO:8. 3310 | 26: |-- 1-808" | 0-5 | 18 | O38 | 25 3 1-2 tale OMNMRO: 5 iht2-5 (93-5 1 9.0" | c4-O7} O4-] 3:1. 1.°0-4 bh 1-1 4 3:8; |, 3-2mO-4alO-5 |, 4-5 | 43 | 5:9] 1-5 | 0-2 | 1-6 | 1-2 | 1:3 5 5:2" 6:5) |) e1eOM! 70:5"| °3-5| 4-1 | 1-0 | 0-3 | -0-3.] 04 | 0-9 | 5-0 6 3:8} 5-8) | (1-6. | 0:7 18 | 66] 14 | 06 | 0-1 @:5 | 2-97 | 2-0 a 0-1 1-3 ateae lee -3.n24-Or | ©2-3 | 21:0) 10-7 | 20-5.) 1-0 | 3:7 | 0:4 8 0:54) O-Velmelevi2-91 1-7 | 2-1 °| 21 | 0-9 | 0:7 °) “Ha | 19°] 2:5 9 0:47 | "0-65 |) 0:9mP0:8 | 11-4: | 40°] 3-8 | 2-0 | 2.0 |.1-3)) 00 | 4:3 10 6:25 | l-Ouees-amina-l- | 0-7 | 1-2 | 0-47) 31 | 1-1] 06} 0-2 | 23 11 3-8 | 1-8 || (3:8 ami mtOe aed 13) |) 11-44) O44 008 8-2 | 7-7 12 05g) 3:7 aleelemeieetG. || S00) tl.) 1:3-| 1-2 | 0:39) 07°) 0-5 | 1-6 13 0:6 | 6-1°]), 0-591" 2-6 | 02-0 | 0-4 |] 0.5 | 04 | 05 | 28 | 0-2.| 0-2 14. 0-8 1-1 2-9 6:7 0-7 0-4 2-7 1-1 1-1 1-6 0-1 5:8 15 0°60) 21-20 ew O:7amlNeG-5) || 0:9) 10-2" | 1-5-1 79.7 | 0.7 |. 2:0 |.1:8 | 3.8 16 0:47) 0-5. O:9mlhn 0-3) | 14=| 0:2 | 0-8 | 1-8 | 09°] 3-1 | 31 |° 5:0 17 127 | 0:7: \ 0:0 0-3 11-7 0-2 | .0-5. |. 0-8. | 1-2 | 3-4 | 2:4 | 0-6 18 1¢90| 20:3 st oeeO's) | 2:4. 10:5 | O38 | 1-1] 1:9 | 7-3 | 23 | O9 19 e7 o)00:29 |) 25min? | 9-6 1 0:8. | 0-5 | 2:5 | 20] 3:9 | 4:3 |. 2:5 20 BeQv old) aad sealeO26 (1-4 1" 0-7-9) 1-3:1))/5-0/)) 4.2) 8:9" | 3-3] 24-3 21 2:0) 0-6) so-Sele Ors: 2-1 | ted Vt -4) 1-68) 348 | 8-2 | 1-5 | 86 22 1-6 0-6 | 6-2 1-3 2-0 2-4 1-6, 2-4 3-6 1-7 0-3 7:8 23 6:3) 7.0:5)) ea omlnel2")) 0-5) | 0-6 | 1-3 1-27 1 O9 | 1-7") 0-6} 4:3 24 1-8 2-2 0-9 0-8 1-0 1-0 0-6 1-5 1-1 2-4 1-0 2-9 25 APG 1:2 | aoe Osdin |i O-5--|- 1-0 | 0:6.-|.01-7 ||..2-6,| 1-7 | 3-3) 2.3 26 Se7 el ase lm osoameeasoe |) 2-5). 1-0) |) 2.0 | 2-8 |) U8 |. 3-6 | 46.| 6-6 27 0-7 0-6 6-3 4.2 1-3 1-8 2-8 1-6 4-3 3°5 6-2 7:6 28 1:5) (2:3) dstomie2e2 | 1-4.) 7:0 |. 0-9 | 01 | 32) £8 | 24.| 4.6 29 0-7 3-6 1-9 1-5 2-2 0.4 0-3 2-2 1-7 8-3 4:8 30 0-2 AMMA -Ge i 2) 2517-3 0.7) | 9.7 | 9.4 | 8.5 | 6.0 31 1-0 3-0 0-6 1:3 0-6 1-7 1-8 MAG. AND MET. oBs. 1845 anp 1846. 58 RESULTS OF MAaKERSTOUN OBSERVATIONS, 1845. TABLE XXIX.—Means of the Maximum Pressure of Wind between the Hours of Observation, for each Month in 1845. March. Ib, TABLE XX X.—Means of the Maximum Pressure of Wind between the Hours of Observation, for each of the Astronomical Quarters, and for the year 1845. Mak. Feb. ae || Nov. ||. eb. M. T. March. (ear. ) Dec. March. j April. anes) || dian April. h. h. lb. "4 5 r 5 lb. ! 1b. 11—12 86 0:75 || “oO: 58 ||| 0-6 1:07 1-09 19-18 0-71 | 0-4 : 6 | 1-04 Neily/ 13—14 : 0-76 : 64 : 1-09 1-24 14—15 86 0:76 4! 5 6 : 0-98 1-12 15—16 zr 0-79 46 : 2 : 0-99 1-11 16=-17 : 0-69 ; : : d | 0-87 1-05 17—18 0-78 j 56 {| 0- 5 5 || 0-97 0-91 18S—19 0-78 : : : | 0-94 0-81 19—20 0.82 : 5: g 7 | 0-96 0-72 20—21 F 1-03 96 6 : ( 1:10 | 0-81 21—22 1-12 : Sil) Os ‘ | 1-06 0-75 22. 93 1-12 14 ; : | 1-05 0-69 PRESSURE OF THE WIND, 1845. 59 TABLE XXXI.—Hourly Means of the Maximum Pressure of Wind within 10™ at the Observation Hours, for each Month in 1845. KP OCOOCONOUKRWNKY OS — TABLE XXXII.—Hourly Means of the Maximum Pressure of Wind within 10™ at the Observation Hours, for each of the Astronomical Quarters, and for the Year 1845. KH COOANAaAKRWNHWEeE CO: — 60 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XXXIII.—Number of Times which the Wind blew from each Point of the Compass at the together with the sums of the Pres- Wind blowing from January. February. March. | April May. June. Times. | Press. || Times. | Press. || Times. | Press. Foe Press. | Times. | Press. || Times. | Press. Ib. Ib. ris | Ib. Ib. Ib. 1), 0-4 7 | 47 25) | -o0-1 |) 18 | 45-2 | 19 |\opts IMO sansa Bil 0:7 5 | 14 | 14 | 11-4 | 26 | 59-4 | 18 | 201 aay | 2 | 0.2 6 | 24 | 98 | 158 | 31 | 43-2 | 86 | 682 elle PHO av) 3.0 2) | 03 | vagal ie:6. || 16> | 12-70) 1095) 67a 2 | 03 6 | 09 3. | 0-4 Ielas, || 5-1 ||| 36 | 11-0 || 104. | Go:7 anions Meze i ae Bil 0:9 Sauer! 15.| 4:6clledeupador 2 | 14 1 | 0-6 Gudea wm | i726 | 7-8 | 18 so:3 slemton amon salt 10 301. loaned 57] 3 | 10-5 18) alee 2: i) 1:0 AN 07 4. | SO-op\ ine ages 9 BS. leis 4.2 | 10 | 28 | Buross 2 | 08 21 05 2.0 2.0 | 6, ede? 3 | 0.8 EB | ales 3 | 12 ae) on Ll Beil) 12 Bil (0%4 3] 10:9 Li, | 2:8 5 |) 0 a | OF al Ae5 lh OS) 4 | 08 Syebesdes 2 | 18 5 | 29 8 | sail az” lao 12°) 15° | 17-6 0-4 8 | 6:30 lbator N76 5-2 | 11 | 136 5 | 56 | 41 i334 ‘li 28 21). 13.6i)neal elo 90N|| 9 21°2), | 0 (5:9 13) (17-4 3901431691 | 28) al aon 7 1 19 |) 15 | 93 04 | 11 | 56 64 | 666 || 51 | 24.5 || 41 | 501 || 40 | 35-2 10:7 || 47 | 562 26 | 43-8 || 21 | 11-1 || 34 | 54-3 || 12 | 120 89 || 47 | 553 58 | 60-2 || 63 | 43-7 | 35 | 346 || 36 | 29.0 || 24 | 494 || 89 | 666 15 | 44 ] 15 | 13-2 | 15 -| 39-7 || 14 | 10:2 || 19 | 23-6 || 35 | 29-5 12 | 43 |) 181) 4.0 ly 30) \ssae5 7 | 26) 16 »| 9-6) SS alte 10 | 3-9 || 11 | 43° a3 use | 2 | oO) | 7) Soci Reees ieee 3-5 || 12 | 40 | 20 |360 | 38 | 06. 13.] 59 ] 21 | 63 qh 0-8 15 | 16-3 17. | 26-3 lt #3 1-7 7 | 26 : 7M 17 ll 19:1) oom alAO<0 1 | 0-0) | 15)| 11-35) 928 a) aoe 0:9]. 4 | \3.7. | toe atee | 7°) 3:3) on 8) Tors 165 li) 9-40 2119 has |e stemipte 3 | dre Ska tee | is | 50 | 2.6 || 22 | 204 | 30 | 19-0 8 | 168 a2 4 | 23 | 2.1 || 32 | 449 | 93 1170 | 2 | o2 || 12 | 78 | 13 7 07 || 17 | 161 | 33 | 350 | 15 | 240 | 6 | 42 | 5 se I i PRESSURE AND DIRECTION OF THE Wrnp, 1845. 61 Observation Hours, with a Pressure of one-tenth of a pound or upwards on a square foot of surface, sures, for each Month in 1845. | July. August. September. October. November. December. Wind blowing from Times. | Press. | Times.| Press. || Times. | Press. || Times. | Press. || Times. | Press. || Times. | Press. Ib. Ib. Ibe | Ib. || tb: | 1b. ere we ea) 3-0 || 35 | 26-4 || 10 | 10-0 3 0-8 3 | 0-4 5 3-5 N. 2.2 | 21 | 108 Way o5 i 3. | 1.2 | i |, 04 N by E. Sie) 12:2) ||. 21 | 13-5 5 1-6 | 25 | 9.5 6 1-7 NNE. 50 | 19-0 || 15 9:7 Wi et2el, 4:1 10 5-7 | 1 0-4 NE by N. BoM s227| || 14 | 3.1 || 29° | 6:0 8 6-3 1 | 0-1 eae ay NE. 10) || 2:9 2 |\..0:8 3 | 0-6 6 7-2 1.-|' 0-2 || =. me NE by E. 7a 6-8 6 || So:salietsre! 127 4 x9) |) eae. ot ae ts ENE. 0-7 4 | 0-4 || 10 Te Se Ollinecs: a 1 0-2 || =. E by N. 0-9 4 "|| 0:5 9 1-2 3 0-3 E 1 0-1 2 | 0.2 1 0-1 E by S. 1 0-4 3 103 4a | 0-4 3 1-Oe |) oe “Ay He A ESE. 3 2.5 3 0-9 | SE by E 7 2.2 2 4 0:3 4 | 0-5 || 10 2.2 4 | 25 1 0-1 SE. 1 0-3 1 0-1 ra A 2 0-4 Gi alenaeae llmnk fe SE by S. 15 | 4:5 5 0-9 || 10 | 3-5 || 10 Panik a4et) qs oY a SSE. 3 2:0) || --- 28 a 1-6. || 11 2.4 || 13 9:0 || =. de S by E. 15 || 21-8 6 1-725} ae 29 || 15 2-8 || 35 | 18-5 5 2-0 S. 3 1-5 8 3-3 3 2.0 |} 11 4.5 || 35 | 36-7 | 12 | 10-5 S by W. 26 | 19-6 | 32 | 17-4 || 48. | 17-3 || 56 | 265 || 68 | 49-2 | 66 | 70-1 SSW. Hemet te 24 =| 19-8 Ni 37001 19-7 ||. 67 | 45-3 |, 87 | 39-9 | 89 | 85-2 SW by S. 52 | 42.4 | 43 | 20-1 | 74 | 34.1 || 147 |109-6 || 66 | 63-7 || 102 | 101-3 Sw. | 23) | 19-9 || 16 | 7-8 || 33 | 22-2 | 64 | 62-6 || 40 | 39-7 | 30 | 37-4 SW by W. | a7 23-4 || 41 | 11-9 || 22 | 13-1 || 39 | 30-8 || 19 | 14-0 | 24 | 280 WSw. | IEMs sell |, 5-2lleeso5 | 12 | 13.3 |: 4.>| 34 | 18 | 23:0 W by S. 15 5-0 || 29 9-6" tion 5:2) 33 | 81-1 AW Oba We 44s 1167-6 Ww. | 8 1-4 9 3:04] eee ae 9 | 15-4 1 0-4 | 21 | 29.9 W by N. 10 3-8 || 21 | 12-6 Bal) (2:8 6 | 12-4 4 15 |) 22 | 35.1 WNW. | 2 | 0-5 7 1-5 1 1-2 4 2.8 6 | 14.0 NW by W. . eee 3-0) | 026 © | 16-35-15. |) F4 As NES 57, 40:4 920 || 35-5 NW. 3 0-6 14 | 10-7 ai 7:8 2 0-7 31 50-1 NW by N. mee ss | 33 | 18.1 || gol |) a5 2 | 03 Geter yh eae 47-0 NNW. 6 1-7 || 16 9-7 2 1-1 4 1-8 A 10:8)" lhe 3) hh, a'729 N by W. MAG. AND MET. oss. 1845 anp 1846. Qa 62 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XXXIV.—Number of Times which the Wind blew from each Point of the Compass with the swms of the Pres- Number of times which the Wind blew from each ESE. | mm 0 we: _ PONNAOHROCONUNNOCOWWUANANAD — SNHWHUENNWWONKONKBKBOW HEH BWR Ww — BOWE AWAITO OWE Oe: PWR WwW wenww: 1 1 1 33 14 59 22 105 | 80 ce DERNMONWWHENMUNNTEPOAWWHRP WWD Www FRED NWUNDOWNTMDOMDNAWWEE EPH D: BWP NWUNUWODRFAhUNwWAwWe Ww: PORE ROOWANUWwWNORhNDe: BENWNUANEWwWaKhNhaAwWwnNeNwNwDy: WHOWHOWRITIRMRBAWORONNWHHHE DY We bw bo ; | | | CO bo Sums of Pressures with Ib. Ib. Ib. 0-1 o DANA BMHOHUIAdMah Mw wdTOUNM oe AO: crt WWODhRMUWAOMNAE wd O MN wa A: 0-4 nese Or! 0-6 wad 0-1 0-1 we. Ono: ND NO WO SO OOo OO Oe TS TSSNUUNWYWNYONS, COOwewkNTONWANW ND: .eesorewonresc, Pa oo ot 91 0 0 te Fg Fel et Foxe BORCS AIBO ORO AHS DO RRO OU AIS ho Comal Ae re a Ne ROE COI Osa 2 OO On On Ors HENNA BRORDANTNDARE ARON WwWNHOeH Ow: RK OOONOURWNFE OS a no. i) Ww { SI Te) 118-2 |170-5 |130-9 |129-2 PRESSURE AND DIRECTION OF THE WIND, 1845. 63 with a Pressure of one-tenth of a pound or upwards upon a square foot of surface, together sures for each Hour in 1845. Point of the Compass at each Hour in 1845. 2 4 NNW. SSW. : WSW. 9 WNW. | | | — CWW HOE WAT Do SCHR NUOAUNUADORD _ DERWUDUOAKAOD — _ WWRENIWOUNARAKRAONHE ATA UNWOAKRUASD — oo — RB ONOWONANTROOADS _— —: wre Do — — bo — = bo bo DD — NTVIOR OHH DAADADOO PNWARBUNUNAHRAUNAVTWANNIUNWWOWR pee WNHDOMA OTH NK NINWAAUNANMOWVNIHOSHSVM.L FOO ON OUR WHE Oo MNO MOKROMOOVY —_ — | ——___—_ 188 | 168 319 121 | — for) or Tb. Ib. 1b. 26-4| 11-3] 3-6 25-4] 12-5] 8-2 21.6| 12-7| 24 18-9] 21.8] 7-7 28-9 25-7 22.4 23.4 32:8 28-7 26-9 37-2 31-5 42.5 40:5 29-6 18.9 17-5 21-9 16-9 30-9 23.2 21-7 40-2 PANO SH ow pwemoerAA Vd KH SCOCON AUB WNWeE OS tet 653:6 . : . -7 |116-6 | 40-7 64 RESULTS OF MAKERSTOUN OBSERVATIONS, 1845. TABLE XXXV.—Sums of the Pressures of the Wind in Table XXXIIL., resolved into the Four Cardinal Points of the Compass, together with the Value and Direction of the Resultant, for each Month, for each of the Astronomical Quarters, and for the Year 1845. _ Resultant. ‘ Sums of Pressures resolved into Period Means with reference to Beet ING E. Ss. W. Sums. Whole No. No. of Obs., Directions. of Obs. Wind blowing. | 1b Tb. Ib. Ib. Tb. lb. Tb. ° January 18-0 13-6 223-6 125-7 234-2 0-36 0-60 S. 29 W. February 103-5 16-6 124-2 140-1 125-2 0-22 0-28 W. 9S. March 158-6 35-6 166-1 281-4 245-9 0-39 0-46 We US: April 208-4 80-5 118-9 69-7 90-1 0-15 0-21 ING | 7610p May 248-0 144-9 70-9 110-3 180-4 0-28 0-32 ING ATE DS June 51-1 20-2 198-5 164-0 205-9 0-34 0-45 S. 44 W. July 62-5 46-3 120-4 107-5 84.2 0-13 0-18 W.43S. | August 113-4 18-2 62-8 106-6 101-9 0-16 0-21 W. 29 N. September 40-6 14-6 84-2 93-7 90:3 0-15 0-22 W. 29S. October 39-3 27-7 204-3 269-4 292-7 0-45 0-51. W. 348. November 6-1 11-5 231-5 150-2 264-7 0-44 0-70 S. 32 W. December 132-5 1-0 255-6 431-3 447-6 0-69 0-84 W.16S8. Astron. Qrs. ‘Winter 156-6 26-1 710-7 707-2 878-0 0-46 0-68 W. 39 8. Spring 470-5 132-7 409-2 491-2 363-7 0-20 0-26 W.10N. Summer 361-6 211-4 389-8 381-8 172-7 0-09 0-11 W. 9S. Autumn 193-3 60:5 351-3 469-7 438-6 0-24 0-30 W. 2158. | The Year. || 1182-0 TABLE XXXVI.—Sums of the Pressures of Wind in Table X XXIV., resolved into the four Cardinal Points of the Compass, with the Value and Direction of the Resultant, for each Hour in 1845. Resultant. Sums of Pressures resolved into Means with reference to N. E. Ss. W. Sums. Whole No. No. of Obs., Directions. of Obs. Wind blowing. mM roOnwWNwWwWhW Wh w oe eles aa 38. 88. 25S: 8S. OS. 78. 18. O08. 338: 58. 58. 8 8. 58. 78. 68. 88. Ish 48. 88. 98. 0S. 38. 68. 58. =OODTANARWNHHO OW eB bo Dh —_—_— EXTENT OF CLOUDED Sky, 1845. 65 TABLE XXXVII.—Differences of the Directions of Motions of the Lower and Upper Currents of Air, as deduced from the Comparisons of the Direction of the Wind and the Motions of the Clouds. | Quadrant N. to E. Quadrant E. to 8. Quadrant 8S. to W. Quadrant W. to N. | Currents. / | No. of ee Mean || No. of te Mean No. of hes Mean || No. of eoae Mean | iffs. of Sante Diffs. of Result. || Resales Diffs. of Fes Diffs. of R Results. Motion Result. || Results. Motion esult. esults. Motion: Result. || Results. Motion: esult. cee | 42 | 414 WaiGmel e419 162 | +25 47 esse ea AQ whl 10m meee See Olea Ie re O94 15 h(t As, '9 Ga 7 0 1 0 as 0 9 0 ; : 14 | +32 | 12 | +24 | 110 | +41 41 | +29 rae ees) 22) ae ta 418) £13 || 10’) —14) +36 || 8 | '—25 | 419 ae mat 0 anrO 0 es} 0 3 0 : ; [i nsteal eestor satis gat | 51 | +23 23 | 424 wee minus) 99' | Sone 6 Fe 32 eed ||) 00 iS je} TABLE XLVIII.—Mean Temperature of Evaporation at the Observation Hours for each Month, for each Astronomical Quarter, and for the Year 1846. Makerstoun Mean Time. January February March April May June July August September October November December Nov., Dee., Jan., Feb., Mar., Apr., May, June, July, Aug., Sept., Oct., The Year Or or Or Or BI ma ho Oost PRESSURE OF AQUEOUS VAPoUR, 1846. 71 TABLE XLIX.—Daily and Weekly Means of the Pressure of Aqueous Vapour, in inches of Mercury, for the Year 1846, as deduced from Tables XLIII. and XLVII. March. in. [0-297] TABLE L.—Pressure of Aqueous Vapour, with reference to the Moon’s Age and Declination, for 1846. Mean Mean After Mean After Mean {f{ Moon’s | Pressure | Moon’s| Pressure || Moon | Pressure | Moon | Pressure Age. of Age. of farthest of farthest of Vapour. Vapour. || North. | Vapour. | North. | Vapour. | Day. in. Day. in. || Day. in Day. in 15 0-333 0 0-316 | 0 0-311 14 0-314 16 +327 1 301: | 1 313 15 307 Vii +320 2 +292 2 298 16 306 18 319 3 +298 3 286 17 313 19 -315 4 317. 4 283 18 Biai7/ 20 -305 5 +312 3 301 19 326 21 +313 6 -317 6 311 20 313 22 +297 i +317 7 325 21 317 23 +298 8 +313 8 306 22 323 24 301 9 +315 9 +308 23 +329 25 :317 10 +315 10 -307 24 +321 26 -305 11 -313 11 -321 25 -296 27 323 12 +299 12 -326 26 302 28 -318 13 304 || 13 318 27 -309 29 +329 14 -315 RESULTS OF THE MAKERSTOUN OBSERVATIONS, 1846. TABLE LI.—Mean Pressure of Aqueous Vapour at the Observation Hours for each Month, for Makerstoun Mean Time. January February March April May June July August September October November December Nov., Dec., Jan., Feb., Mar., Apr., May, June, July, Aug., Sept., Oct., The Year each Astronomical Quarter, and for the Year 1846. TABLE LIT.—Mean Relative Humidity of the Air for each Week-Day and Week in 1846, Jan. Feb. 0-757 | [0-851] 831 -807 891 +865 [ -854]| -881 -906 -807 -896 878 +846 -783 -883 | [ -852] -872 879 | +850 +929 [ -900}} -834 922 -866 +952 837 922 -770 932 |[ -815] -990 821 -956 -806 |{ -933]| -791 916 801 | 898 +820 +905 895 986 |[ -856] | 9700 /Messs 957 -885 [ -919]| -853 -920 ‘837 +820 “840 +860 -890 +832 | 805 “915 March. April. May. June. 0-639 715 661 639 603 575 [ -711] 865 791 795 737 746 713 [ -701] 705 .667 637 .756 714 795 [ -770] 629 940 786 -808 850 -782 [ -809] 742 836 Saturation being = 1. July. Aug, 0-838 0-898 ‘742 |[ -892] -863 ‘835 -816 “821 [ -810] -892 -896 S11 -689 -980 +857 -919 -942 [ -861] -790 +843 -744 +830 [ -820] -784 831 -8S71 795 -769 “816 -916 858 | [ -872] 837 -865 “844 -932 [ 832] ‘S78 -798 927 895 857 759 -867 S71 [ -860] -743 +839 767 “S34 [ 835] -839 -875 787 -828 ‘$56 -928 +895 957 [ -836] 951 -845 Sept. 0-793 -840 +850 -870 -872 [ -854] 847 Sasa wo “J bo uy Oct Nov. Dec 0-872 | [0-898]} 0-898 -886 -837 S77 829 -889 -$99 { -852] “883 -895 +859 -930 -865 827 873 | [ -890] +842 “901 835 -878 |[ -929]| -943 -919 -944 -904 -868 954 | -796 [ :871] 970 -798 -892 926 | 875 753 903 [ -846] -914 885 +855 -946 |[ -891] -890 -963 857 -$65 -966 -904 -909 |[ -931] “S74 -898 -925 858 | -954 -$90 -846 | [ -923] -899 *859 972 905 |[ -895] | 906 715 903 -900 -903 933 | 902 [ -886] 972 -S66 -943 S71 -933 960 “888 | [ -932] “S91 -893 -932 946 | [ 883] 979 957 S74 -982 -985 RELATIVE HuMIDITY OF THE AIR, 1846. Te TABLE LIII.—Mean Relative Humidity of the Air, Saturation being = 1, with reference to the Moon’s Age and Declination, for 1846. After - Mean i Mean Noon Mean Mean Relative 5 Relative farthest Relative Relative } Humidity. Humidity. |) 744, | Humidity. Humidity. } D 0-844. -830 825 814 +848 +833 863 851 0-827 “859 -845 -839 -866 -850 -860 -862 -867 -823 -870 827 -854 +826 833 +838 847 835 823 ‘847 864 WCONANMKRWH EOF TABLE LIV.—Mean Relative Humidity at the Observation Hours for each Month, for each Astronomical Quarter, and for the Year 1846. Makerstoun 7h gh Mean Time. i , oe ; ; : : : January . . 0-888 | 0-895 February : : F : : : : 841 862 March : 3 : : : ‘ : .848 “885 April : : r : ‘ 3 9 87] 924. May : : ; : : ‘770 | +838 vane : : : ; ; ; : -730 848 July é i 795 4 F F : 849 898 August : A 4 A : : : -862 .929 September . : 4 A : : i -890 -935 October . : : . . : . -907 +925 November d 0 i a 4 dj 0 -899 914 December : : 3 : : : : -910 -919 Nov., Dec., Jan., : . . . : : . -899 -909 Feb., Mar., Apr., : . . : . - . +853 -890 May, June July, : . . . : . : -783 ‘861 Aug., Sept., Oct., . : : : . : . -886 +930 The Year, . . . : . . : -855 -898 MAG. AND MET. oss. 1845 anp 1846. T RESULTS OF THE MAKERSTOUN OBSERVATIONS, 1846. TABLE LV.—Daily and Weekly Means of the Height of the Barometer in 1846. TABLE LVI.—Mean Height of the Barometer at the Observation Hours for each Month, for each 74 Dey: | Jan. Feb. in. in. 1 29-394 |[ 29-336] 2, 30-041 | 29-484. 3 29-948 | 29-296 4 |\[29-758]| 29-493 5 29-808 | 29-450 6 29-606 | 29-451 7 29-754 | 29.276 g || 30-044 |[ 29-730] 9 30-245 | 30-099 10 || 30-047 | 30-197 11 |[29-769]| 29-905 12 || 29-661 | 29-896 13. || 29-352 | 29-859 14 29-266 | 29-925 15 29-413 |[29-892] 16 29-596 | 29-978 17. ‘|| 29-540 | 29-899 18 [29-188]| 29-793 19 28-935 | 29-752 20 28-685 | 29-774 21 | 28-961 | 29-684 22 || 28-663 |[29-456] 23 | 28-865 | 29-380 24 | 29-159 | 29-105 25 ||[28-913]| 29-041 26 28-763 | 29-335 27 29-015 | 29-341 98 «|| 29-012 | 29-420 29 =| 29-078 30 29-383 31 29-285 Makerstoun Mean Time. January February March April May June July August September October November December Noy., Dec., Jan., Feb., Mar., Apr., May, June, July, Aug., Sept., Oct., The Year March. TM, [29-259] 29-397 29-169 28-892 29.212 29-265 29-377 [29-681] 29-941 30-053 30-239 30-266 29-955 29-604 [29-511] 28-707 29-078 29-458 29-438 29-479 28-990 [29-124] 28-823 28-971 29-042 29-183 29-377 29-412 [29-381] 29-847 29-421 April. in. 29-046 28-913 29-016 29-273 [29-100] 29-060 29-125 29.214 29-401 29.468 29-246 [29-424] 29-227 29-513 29-690 29-839 29-727 29-844 [29-848] 30-000 29-851 29.825 29-790 29-727 29-781 [29-766] 29-664 29-733 29-900 30-025 May. in. 29.955 29-860 [29-688] 29-705 29-369 29-214 29-352 29-563 29-607 [29-621] 29-694 29-709 29-803 29-954 29-777 29-475 [29-358] 28-798 29-031 29-113 29-579 29-837 29-977 [29-810] 29-834 29-833 29-801 29-977 30-034 29-982 [29-980] June. 29-945 29-962 29-978 29.929 29.884 29-819 [29-711] 29-624 29-493 29-520 29-801 29-909 29-890 [29-957] 29-977 30-088 30-076 29.965 29-861 30-064 [29-636] 29-668 29.205 29-055 29.264 29-360 29-361 [29-356] 29-303 29-360 July. Aug. in. in. 29-490 29.724 29-615 29-768 29-813 [29-557] 29-119 29-445 29-581 29-553 29-670 29.807 [29-635] 29-714 29-514 29-551 29.282 28-995 28-911 [29-273] 29.556 29.423 29-474 29.392 29-435 29-603 [29-641] 29-715 29-821 29-883 29-939 29-918 | 29-929 29-660 29-722 29-736 29-730 29-596 29-424 29-631 29-626 29-748 29-313 29-608 29-418 29-492 29-311 | 29-463 29-494 29-689 29-832 30-078 30-104 30-003 29-899 29-917 29-884 [29-783] | ([29-847]| 28-982 | 29-648 [29-626] [29-434] [29-867] ‘[29-304]| [29-960] Sept. Oct. 29-608 29-486 29-434 \[29-275] 29-247 in. 30-089 30-043 30-036 30-053 29-961 28-891 28-936 29-042 28-934 [29-170] 29-436 29-752 28-923 28-718 29-029 29-258 [29-031] 29-290 29-190 28-702 28-779 29-298 29-247 29-564 29-822 30-128 30-194 30-297 [30-108] 30-057 30-007 29-963 29-824 29-756 29-499 [29-561] 29-563 29-522 | 29-200 29-195 | [30-119] Nov. in. 29-425 29-318 29-422 29.735 29-498 \[29-789]} 29-958 | 30-121 30-273 | 29-998 30-323 | 29.585 30-314 | 29-501 30-325 | 29-613 30-257 |[29-483]] - 30-137 | 29.335 | [29-908]) 29-371 29-842 | 29-491 29-497 | 29-592 29-389 | 29-699 | 29-283 | 29-456 | 28-760 [29-187]} 29-030 | 28-749 | - [29-152] 28-818 29-388 | 28-810 | | 29-183 | [29-762] 29-599 29-664 29-721 29-896 29-911 29-997 29-422 | 29-315 | 29.785 30-025 29-321 | 29-891 29-099 | 29-926 29-470 29-919 | 29-741 Astronomical Quarter, and for the Year 1846. 652 702 -558 685 5727 .299 659 595 | 5487 | -5203 | 6373 5708 5692 | | 613 402 +524 643 695 550 678 714 298 646 598 5473 | “5130 -62983 | 5633 | *3632 [29-504] : 29-621 30-036 | '[29-892)} 30-128 30-134 } 29-772 | 30-252 30-279 | TABLE LVII.—Diurnal Range of the Barometer for each Week-Day and Week, for 1846. March. 5) cs in. [0-211] 252 246 377 211 071 -300 217] -235 -099 388 -231 243 449 383] 482 ‘704 OONAMA WYO TABLE LVIII.—Diurnal Range of the Barometer, with reference to the Moon’s Age and ATMOSPHERIC PRESSURE, 1846. Declination, for 1846. . Mean " Mean uN Uae S|! Diurnal Bact S|) Diurnal fe f Os Range. be Range. Eine Day. in, Day. in. Day. 15 0-204 0) 0-221 0 16 -167 1 -147 1 17 -208 2 +248 2 18 -200 3 +248 3 19 -192 4 -207 4 20 +209 5 -182 5 21 +228 6 “191 6 22 +255 7 +257 7 23 -146 8 +202 8 24 -298 9 -190 9 25 179 10 -189 10 26 -187 11 “152 11 27 219 12 “181 12 28 +212 13 -155 13 29 -253 14 °155 Mean Diurnal Range. After Moon farthest North. 15 76 RESULTS OF THE MAKERSTOUN OBSERVATIONS, 1846. TABLE LIX.—Extreme Readings of the Barometer for each Month; Extreme Mean Daily Heights for each Month; and Extreme Diurnal Ranges for each Month, together with the Ranges and Means of the Extremes, for 1846. Extreme Readings. Extreme Daily Means. Extreme Diurnal Ranges, ; Month. Highest. Lowest. Range.| Mean. Highest. Lowest. Range. | Mean. Greatest. Least. a ni aie oS ide She ine in. in, a. in. a. in. in. ins 6 id, || pene ile as ; Jan. 9 0) 30-304) 21 18 |28-498) 1-806 |29-401 9 | 30-245) 22 | 28-663) 1-582 |29-454 || 1 |0-761) 17 0 035 1 Feb. 9 23 | 30-268) 24 22 )28-863 | 1-405 |29-565 || 10 | 30-197] 25 | 29-041} 1-156|29-619 || 3 |0-539| 13 0-031 11 10) 30-380|16 8/28-492) 1-888 |29-436 || 12 | 30-266 16 | 28-707) 1-559 |29-486 || 21 |0-730} 19 |0-022) April | 29 21] 30-058] 2 18 /28-823 | 1-235 |29-440 || 30 | 30-025) 2 | 28-913] 1-112|29-469 |} 3 |0-436| 7 10-032] ! 28 18/30-066/18 4/28-772) 1-294 /29-419 || 29 | 30-034; 18 | 28-798] 1-236 |29-416 | 21 |0-496)| 26 0-034} 7 June || 16 10| 30-115] 23 18 /28-988 | 1-127|29-551 || 16 | 30-088| 24 | 29-055] 1-033 |29-571 || 23 (0-500; 2 0-023 hy July | 30 10|29-986|18 628-778) 1-208 |29-382|| 30 | 29-939] 18 | 28-911) 1-028 |29-425 | 16 0-437; 9 0-042) ) Aug. || 24 20/30-132)13 2)/29-118) 1-014 )/29-625 || 25 | 30-104) 18 29-311) 0-793 29-707 || 13 |0-579| 5 0-025} j Sept. || 12 10| 30-351|29 4/29-027)| 1-324 |29-689 | 12: 30-297) 29 | 29-099] 1-198 }29-698 || 30 0-432) 3 |0-032 | Oct. || 27 0] 30-061/21 4/28-582)| 1-479 |29-321 | 27 | 30-025) 21 | 28-702] 1-323 |29.363 || 14 |1-026) 30 |0-090 6 8 Nov. || 10 0/| 30-352) 20 28-267 | 2-085 |29-310 | 12 | 30-325) 20 | 28-760) 1-565 29-542 20 |0-970 \ o.osal | Dec. || 30 22| 30-304] 22 18/28-681| 1-623 |29-492]] 31 | 30-279] 21 | 28-749) 1-530|29-514 || 25 |0-537| 28 0-047] | ie t TABLE LX.—Daily and Weekly Means of the Pressure of the Wind, in Pounds on the Square Foot of Surface, deduced from the greatest pressures occurring between the Observation Hours, in 1846. OWBDNMHNBWNe ee ee NRF OoannN GS PRESSURE OF THE WIND, 1846. (ae TABLE LXI.—Daily and Weekly Means of the Pressure of the Wind in Pounds on the Square Foot of Surface, deduced from the greatest pressures observed within 10™ a¢ the Hours of Observation in 1846. March. OWONMHwfP Wwe TABLE LXII.—Mean Pressure of Wind with reference to the Moon’s Age and Declination, for 1846. After After Moon’s Pressure Moors Pressure | Moon Pressure NOOn Pressure of of of Punt hest of Age winders’: | Wind. | soe | Wind. | sortn.| Wind. Day. 1b. Day. 1b. NV cc DY 1b Day lb OMNIA ANpwWMH Of 78 RESULTS OF THE MAKERSTOUN OBSERVATIONS, 1846. TABLE LXIII.—Maximum Pressure of the Wind in each Civil Day in 1846. Jan. Feb. March. April. CON DN BP w OO = ROU DO) ON Oh EN NSN NN SS Se eS eS SS eee anr nar wonrerctd SC On Gok |W HO KH OC 6-1 1-2 7-0 2:8 1-6 2-5 8-2 3-1 2-6 0-5 1:5 0-2 0-8 0-4 1-5 0-8 0:5 0-1 0-2 0-1 3+] 11-0 1-8 3-7 3:8 2:1 2-6 1-1 10:7 June. July. Sept. 0-7 1-5 1-0 1:7 0:5 0-3 0-3 0-6 0-4 1-5 0-4 1-2 0-4 0-5 PRESSURE OF THE WIND, 1846. 79 TABLE LXIV.—Means of the Maximum Pressure of Wind between the Hours of Observation for each Month, for each of the Astronomical Quarters, and for the Year 1846. Makerstoun Mean Time. January February March April May June July August September October November December Noy., Dec., Jan., Feb., Mar., Apr., May, June, July, Aug., Sept., Oct., The Year TABLE LXV.—Means of the Maximum Pressure of Wind within 10™ at the Hours of Observation for each Month, for each of the Astronomical Quarters, and for the Year 1846. O_O ee nae pe eeseun 17%, 19», 21h, 230, 1, 3h, 5h, 7, gn, Mean Time. lb. 1b. lb. lb. 1b. lb. lb. lb. Tb. January 0-48 0-37 0-36 0-51 0-49 0-42 0-47 0-58 0-44 February 0-42 0-37 0-53 0-75 0-57 0-85 0-49 0-22 0-32 March 0-57 0-44 0-93 0-72 0-71 0-95 0-58 0-49 0-40 April 0-19 0-31 0-50 0-55 0-59 0-61 0-41 0-26 0-18 May 0-20 0-44 0-80 0-96 0-97 0-99 0-76 0-42 0-27 June 0-18 0-30 0-46 0-51 0-61 0-52 0-53 0-31 0-28 July 0-29 0-40 0-76 0-68 0-72 0-78 0-53 0-46 0-34 August 0-11 0-16 0-32 0-35 0-25 0-30 0-26 0-16 0-10 September 0-10 0-13 0-20 0-36 0-29 0-29 0-21 0-18 0-10 October 0-34 0-33 0-43 0-59 0-50 0-55 0-43 0-43 0-41 November 0-37 0-40 0-43 0-59 0-59 0-59 0-49 0-56 0-42 December 0-31 0-31 0-46 0-41 0-35 0-47 0-38 0-39 0-31 Noy., Dee., Jan., 0-39 0:36 0-42 0-50 0-48 0-49 0-45 0-51 0-39 Feb., Mar., Apr., 0-39 0:37 0-65 0-67 0-62 0-80 0-49 0-32 0-30 May, June, July, 0-22 0-38 0-67 0-72 0-77 0-76 0-61 0-40 0-30 Aug., Sept., Oct., 0-18 0-21 0-32 0-43 0-35 0-38 0-30 0-26 0-20 The Year 0-30 0-33 0-51 0-58 0-55 0-61 0-46 0-37 0-30 80 RESULTS OF THE MAKERSTOUN OBSERVATIONS, 1846. TABLE LXVI—Number of Times which the Wind blew from each Point of the Compass at the together with the sums of the Pres- January. February. March. April. May. | June. Wiud blowing: from Times. | Press. || Times. | Press. || Times. | Press. || Times. | Press. || Times. | Press. | Times. | Press. een er a Ib. lb. Ib. lb. Tb. lb. Nine Le Pan 1 Wn 7 Teese) 13. | 13-7)blea ee mlanOro Il SOs N by E. ie a 1 1-6 a8 “ab Se | noua NNE. 2 | 04 30:9 || 25 | 15-7 7 1-7 Sal 29 NE by N. - 2 | 0.4 2 | 0-8 9 | 44 3.1 0:8 2 || 0.4 NE. 2a nOs2 1 O32 24 10-9) onde sta 9 | 25 NE by E 1 O3e lp 142) U5 1 0-8 1 | 0:4 ENE. 2 | 0.3 11 5-2) = 410) 41855 BOS E by N, 1 0-1 2 |r.0-2 1 0-7 Qrl0s5 E Bia p (2:6 4 | 0-6 6 | 36 1 0-1 E by S. 1 0-1 7 ESE, 2 1-6 1 0-1 5 2-7 2) 1-0 SE by E. 1 0-8 2s 10:2 2 1-9 1 0-2 SE 3-b 0-7 1 0-1 1 0-2 pol Be Sa l0-9 SE by S ThjlenO-8 Deol 0:2 1 0-1 2 | 0-8 SSE. 2 AAiO-3 1 1-0 3. | 0-5 6 | 33 5 3-1 7 | 2-6 | Sby E 2 1-0 22 t 0-4 1 0-2 6 | 5-4 1 0-2 — 8. 13 1-9 9 |. 3-2 || 16. | 30-0 Gie, |) 3-38 1813 pen ate 5 14 | S by W. GU ize 7 5-8 8 9-1 6 3-6 3 29 | 3 | 43 | SSW. 23. "| 14-3 “ 20 | 13:0 || 199),06:9° | 10.) 3-1 || 24) 09-7) 1 sot area SW by S. 15) jai) 14-3 16 | 15-6 || 18 | 25-0 2 | 0-7 || 10) || (9:8) ems iiles | Sw. 43 | 33-6 || 28 | 24.0 || 22 | 22.9 4 | 06 | 17 | 146 | 24 | 206 | SW by W. 13 Wl 15-8%|lp' 42) 2622) OMh ha0:6 2 0:2 6: | 60°] 17 | ssagmy WSW Sie ered 10) -|)).3-9) soa 729 4] 04 | 15 | 99 | 17 | 87 | W byS Tl) 0:7 4 )\gaes 4 | 88 4 | 2:05 sa) ae | 202m Ww. 1 1:0 || 13 | 13-6 Bib | See 5 16 | 14/156 | 7 | 24 1% W by N. 3:1 ||, 3:0 6 | 45 6. || =3-2 1 1.2 4%) soe | 4io| ag WNW 1 | 09 9 | 51 |} 4 | 49 | + + || 13. | 13:9] “2 eos NW by W BulPates did) \eOso 1 | 03 |-.3 | 05] Nw. Taj ex Oi insta SINE a1G5) | Lh RS ha EY Bal pe 7 37) ose NW by N WW) 2081 ean er | eee | | NNW. 1 0-2 3 1-5 3) POS 4 | 1:45 a 1-2 é 0-2 N by W AOS | 2 | 03 | 0-4 | | | PRESSURE AND DIRECTION OF THE WIND, 1846. 81 Observation Hours, with a Pressure of one-tenth of a pound or upwards on a square foot of surface, sures, for each Month in 1846. July. August September. October, November. December. Times. | Press. || Times.} Press. || Times. |} Press. |) Times. | Press. || Times. | Press. || Times. | Press. lb. lb. Ib. Ib. Ib. 1b. 4 1-9 3 0-4 6 0-9 8-8 10 10.2 12 14-2 4 1-2 2 0-5 0-4 2-7 5) 1-6 9 2-1 5 0-5 14 18-5 4 0-7 7 6-6 3 0-7 8 1-3 6 0-8 5 3-6 19 4-1 22 3-9 16 3-5 5 0-5 3 0-3 4 0-8 5) 1-2 1 1-0 1 0-1 Sms se) Ti | Qa 1s) 4a | 83 | o4 2 | 0-2 aor PeOG) || <2 |. OS eRe |e. 0-3 2 0-3 11 2-1 9 1-2 3 0-3 2 0-2 1 0-2 0-4 4 2-0 4 1-6 2 0-2 505 0-2 1 0-3 1 0-1 1 0-2 8 1-2 7. 2-4 4 1-4 3 0-9 cee 3 1-2 1 2-0 2 0-2 2 0-2 4 0-9 8 7:4 13 14-2 1 0-2 3 2-9 2 0-4 1 0-1 4 7-0 3 0-3 9 6-7 i 4:5 6 1-1 12 3-1 36 25-5 4 0-4 6 8-8 7 1-5 6 1-6 4 1-5 4 1-3 1 0-2 30 21-1 21 5:0 16 4-0 44 25-9 30 20-7 13 2-4 12 9-7 6 3-0 5 1-0 5 2-4 5) 3-6 3 1-7 42 28-6 23 10-6 32 11-0 23 11-7 16 9-3 24 9-7 Tamils: | soll ez) 13 | e2 | 03 | 3 | 24 | 15 | Be 19 15-2 12 3-5 11 2-7 15 4-3 3) 1-2 17 2-7 6 4-4 1 0-3 2 0-8 2 0-3 1 0-1 3 0-8 8 4-0 2 0-3 6 1-0 8 1-3 1 0-1 11 2-4 1 0-9 1 0-1 1 0-1 1 0-6 1 0-1 2 0-4 6 2-1 1 0-4 2 0-6 4 1-0 3 0-7 0-7 2 0:5 1 1-1 3 1-0 10 5:5 5 1-4 3 0-5 8 1-4 3 2-4 7 2-8 36 15-0 eee 1 0-2 3 2-9 3 1-4 12 9-2 1 1-0 5 2-2 4 1-8 2 1-1 if 3°5 13 11-2 2 2.3 1 0-1 0-4 6 3:5 3 2-1 6 3-4 MAG. AND MET. oss. 1845 anv 1846, Wind blowing from 82 RESULTS OF THE MAKERSTOUN OBSERVATIONS, 1846. TABLE LXVII.—Number of Times which the Wind blew from each Point of the Compass the square foot of surface, together 1h, Bs Wind blowing from Times. | Press. || Times. | Press. || Times. | Press. || Times. | Press. — ao wm aT OO CO FH OD ow iY) wo ie) FPF wT NY DH Dw FPDowWwuan fF NH NH Oe PRESSURE AND DIRECTION OF THE WIND, 1846. 83 at each Observation Hour in 1846, with a Pressure of one-tenth of a pound or upwards on with the sums of the Pressures. 5h, 74, 9h, 9 Observations. 12 Observations. Mean Pressure, Wind blowing Wind frou Times. | Press. || Times. | Press. || Times. | Press. || Times. | Press. || Times. | Press. || Blowing. 1b. Ib. Ib. Ib. 1b. Ib. ig ean 10 4-9 1-9 8-0 67 53-5 83 71-2 0-86 N. 2 0-9 0-9 0-8 18 19-1 22 21-8 0-99 N by E. 12 7-2 11 7:6 17 4-4 89 51-6 122 61-8 0-51 NNE. 6 1.4 4 0-7 4 0-7 40 13-2 52 17-2 0-33 NE by N. 13 2-5 13 2-5 13 1-6 110 29.2 138 33-4 0-24 NE. 3 1-3 5 1-0 0-3 28 9.4 32 10-0 0-31 NE by E. 10 3-3 10 1-9 0-8 64 20-8 73 23-8 0-33 ENE. 1 0-1 0-4 12 2-9 12 2-9 0-24 E by N. 5 2.3 1-1 6 0-6 41 10-8 51 11-7 0-23 E. . 1 0-1 1 0-1 0-10 E by 8. 0-6 0-1 1 0-1 23 9-8 24 9-9 0-41 ESE. 1-1 1:0 10 3-7 1] 4-1 0-37 SE by E. 1-3 0-5 3 1-3 37 13-1 49 17-1 0-35 SE. 1 0-1 10 4.4 13 5-1 0-39 SE by 8. 6 3-3 2-6 5 1-7 54 33-9 70 38-4 0-55 SSE. al BE TeSualeeeen| 1-2 25 | 17.9 29 | 206 || 0.71 S by E. 18 9-6 15 7-6 6 1-6 136 92-3 163 105-6 0-65 S. 6 3-2 3-8 5 4-7 71 47:8 92 62-0 0-67 S by W. 33 16-2 28 17-9 32 | 16.1 271 164-5 358 | 205-1 0-57 SSW. 9 | 12.5 15 8-9 12 7-6 113 103-2 146 129-4 0-89 SW by 8. 35 | 23-7 41 19.4 27 13-8 298 197-2 383 | 247-1 0-65 SW. 15 11-7 9 6-2 9 6-1 101 66-0 125 81-3 0-65 SW by W. 13 4:8 20 8-3 13 4-9 145 67-5 184 79:6 0-43 WSW. 1 0-1 5 1-0 3 2-2 34 21-8 43 26-6 0-62 W by S. 9 4.0 4 0-8 8 1-7 81 47-1 102 55:5 0-54 W. 5 3-3 3 0-4 2 0-7 31 18-7 35 21-5 0-61 W by N. 8 4.9 4 1-2 5 3-9 50 31-5 66 39-1 0-59 WNW. 1 1-1 2 0-4 23 10-9 26 11-3 0-43 NW by W. 14 6-9 8 6-5 6 3-0 85 34-7 104 43-7 0-42 NW. 1-5 5 4:3 1 0-2 25 17-5 31 20-5 0-66 NW by N. 3-9 6 4.8 5 4-9 49 25-9 62 37-0 0-60 NNW. 0-7 2 1-3 1 0-2 29 15-8 36 19-7 0-55 N by W. 84 RESULTS OF THE MAKERSTOUN OBSERVATIONS, 1846. TABLE LXVIII.—Sums of the Pressures of the Wind in Table LXVLI., resolved into the Four Cardinal Points of the Compass, together with the Value and Direction of the Resultant for each Month, for each of the Astronomical Quarters, and for the Year 1846. Resultant. Sums of Pressures resolved in Means with reference to Whole No. No. of Obs., Directions. of Obs. Wind blowing. ; ; : ‘ : : Ib. January : : : . . : 0-56 February : : d : : . 0-52 March : : . . . 0-79 April : : : : : ; 0-28 May : : b é : ve 0-36 June : July August September October November December Astron. Qys. Winter Spring Summer Autumn The Year. ANARD ND DAD AM = aS TABLE LXIX.—Sums of the Pressures of the Wind in Table LXVII., resolved into the Four Cardinal Points of the Compass, together with the Value and Direction of the Resultant, for each of the Observation Hours, and for the Year 1846. Resultant. Sums of Pressures resolved in Makerstoun Mean Time. Means with reference to N. E. Ss. W. Sums. Whole No. No. of Obs., | Directions. of Obs. Wind blowing. h. lb. Tb. Ib. lb. lb. Ib. lb. C) 17 19-3 6-2 51-2 42-8 48-6 0-16 0-27 W. 418. 19 24-5 8-4 51:8 44-3 45-1 0-14 0-22 W. 378. 21 32-5 15-0 87-1 66:3 74:9 0-24 0-31 W. 47S. 23 36-7 21-8 99.4 75-4 82-5 0-26 0-31 W. 49 S. 1 29-6 20-7 91-6 80-0 85-9 0-27 0-30 W. 468. 3 40-0 24-7 88-9 90-6 82-1 0-26 0-29 W.. 37S. 5 31-0 16-9 73-6 64.7 64-0 0-20 0-24 W. 42S. Uf 28-3 12-0 60-6 51-7 51-2 0-16 0-21 W. 3958. ‘ 9 23-7 6-9 46-7 43-0 42:8 0-14 0-21 W. 32S. Sum of 9 Obs.|| 265-6 132-6 650-9 558°8 | 574-5 0-20 0-26 W. 42S. Sum of 12 Obs.|| 330-1 152-2 7978 687-5 710-8 0-19 0-26 W. 41S. EXTENT OF CLOUDED Sky, 1846. 85 TABLE LXX.—Differences of the Directions of Motions of the Lower and Upper Currents of Air, as deduced from the Comparisons of the Direction of the Wind and the Motions of the Clouds in 1846. | Quadrant N. to E. Quadrant E. to S. Quadrant S. to W. Quadrant W. to N. Currents. | No. of eee of Mean || No. of Hoaer Mean || No. of Sate Mean || No. of ve ee Mean | Results.| yrotion. Result. | Results. Motion. | Result. Results. Motion: Result. || Results. Motion. Result. [} =40 eno3 17a | 20 129 | +929 DTA sO soos eral oe) anes Aaa lege asaion||eetieey||e== or Sei9 Soe er | hs 1 0 4 0 6 0 1 0 : : |) 25 alee Maa leelg 53 | 433 12° || 230 peer minus) 1 —67 | +17 ee) 3 | 6 | —14| +29 4 =38 54213 lo 0 0 0 0 0 0 0 ee il) Beas Opa, 98 V7 eo 23 12) "896 pee TOES) ES NI a) || an ya ee) AO toh Gi) | er liaor | ag 4 0 5 8 0 6 0 A |) 9) | aeaeals 2 | +58 36 | +40 Suinlesesic poet S| 0! | eeealter 45 || =o 158l| 1) 2 Pese|| a po | 496 (| 0 0 0 0 4 0 I 0 , 5 We 3) ge 2G 6 | +52 (Seale 39 WO TI 2 3q ae pes ig IRE 99 || | oO BAL Gua = [oeleaeog:|lN a7 ule onl aro (Rae 0 1 0 3 0 1 0 TABLE LXXI.—Daily and Weekly Means of the Estimated Extent of Clouded Sky, the whole Sky covered being 10, for 1846. ee Jan. Feb. March. | April. May. June. July. Aug. Sept. Oct. Nov. Dec. 1 1-2 [7-9] [8-1] 9-1 10-0 0-4 9.2 7-0 4-9 6-2 [6-5] 4.9 2 4-1 6-1 7:9 8.4 9-1 2-2 8-9 [7-9] 7-1 5-2 9-5 1-2 3 9-8 8-1 10-0 7-2 [9-6] 1-4 9-9 6-2 7-9 1-3 6-6 5-0 4 [6-6] 6-3 7-4 9-9 10-0 1:5 5-9 7-7 9.3 [5-4] 5:4 2-4 5 5-1 6-8 2-7 [9-0] 9-2 5-7 _ [8-8] 7-9 7:0 7 7:9 8-2 6 9.9 7:2 8-9 8-8 9-7 5:3 9-8 2-9 [6-9] 5:8 9-5 [6-3] 7 9.5 5:6 4-6 9-5 6-3 [6-9] 8-1 10-0 4.2 5-3 8-6 6-5 8 8-5 [6-7] [6-2] 10-0 4:3 9-9 10-0 8-8 6-9 6-0 [7-5] 9-7 9 9-1 6-2 2-9 5-4 8-8 10-0 [7-3] 6-3 6-9 8-4 5:8 10 9.3 7:9 9-2 6-1 [6-3] 10.0 71 4:7 2-2 8-4 3-8 4.2 11 [9-0] 7-1 5:7 10-0 4-2 8-2 8-8 8-6 6-6 [8-1] 6-9 7-0 12 9 5:4 8.4 [7-6] 8-7 5:8 [8-5] 8-6 9-2 10-0 10-0 6-4 13 8-4 2-5 8-5 9-3 8-9 7:2 7-0 9-1 [6-0] 7-4 10-0 [5-0] 14 9-8 9-7? 8:3 7:5 4-5 [4:7 ] 9.3 5-6 9.9 10-0 1-5 15 5-7 [7-6] [7-9] 10-0 6-1 4.7 8-7 7-4 5-6 8-4 [8-1] 5:5 16 9-7 9-4 8-5 7:8 4.7 1-3 10-0 [7-8] 8-7 8-7 4-1 5:6 17 9.4 9-2 5:3 10-0 [6-6] 1-1 9.4 9.4 10-0 9-5 9.2 2-7 18 [8-3] 9-7 8-6 10-0 9-5 4-7 9-3 8-9 5:3 [8-9] 5-1 6:7 19 10-0 10-0 3-1 [7-9] 8-5 8-1 [9-0] 6-6 10-0 7:8 4.2 7:3 20 10-0 10-0 3-6 4:8 6:3 8-1 7:8 9.9 [7-7] 8-9 9-7 [7-2] ~ PAL 5:3 9-5 7:7 7-6 4.2 [7:7] 9.9 8-9 6-7 9-9 4-5 9-6 22 10-0 [9-5] [6-0] 7-2 9-5 6-7 75 6-4 6-0 9-1 [6-6] 9-0 23° 7:3 9-7 7-5 9-2 9.2 10-0 9-9 [6-4] 8-1 6-5 6-1 8-2 24 6-6 9-6 8-4 10-0 [7-4] 8-4 5-9 5-8 9-6 9-9 5:7 4-5 25 [7-8] 8-4 5-6 9-4 6-1 5:8 5-2 3-5 8-1 [7-1] 9-7 2-8 26 9-7 9-2 71 [8-2] 6-2 9-6 [8-3] 3:8 9-0 2-5 10-0 1-0 27 5:8 7:3 7:8 8-4 9-0 5:8 9-1 6-2 [8-9] 5-9 7:7 [4-8] 28 7:5 6-8 6-1 6-2 3°5 (7:5 ] 9.7 4.2 7-5 8-8 3-6 8-0 29 7:3 [7-7] 3:9 5-7 6-1 10-0 7:8 10-0 4-7 [5-8] 6-9 30 9-5 8-1 9-9 3-2 8-7 9-3 [6-3] 9-0 3-7 7:4 5-5 31 10-0 8-1 [2-7] 9-6 7:5 9-3 9-5 ee ee eer ee ee ee eee ee eee ee ee ee eee eee ee reac MAG. AND MET. oss, 1845 anp 1846. Y 86 RESULTS OF THE MAKERSTOUN OBSERVATIONS, 1846. TABLE LXXII.—Means of the Estimated Extent of Clouded Sky at the Observation Hours for each Month, for each of the Astronomical Quarters, and for the Year 1846. Makerstoun Mean Time. January February March April May June July August September October November December DWOWTOMNA DWH © wo boc tH oO WONT Ape PRODHANWHON AIAARABHWBAAASTY SCaOhHOWNWAOLH ON ATIATWOHADANASN BARD WAH DWAIN Y | AOorreWweHETIOONWF > aN Nov., Dec., Jan., Feb., Mar., Apr., May, June, July, Aug., Sept., Oct., ES m= WO DWAR ty OH a vu The Year, So x TABLE LXXIII.—Quantity of Rain by the Observatory, Garden, and Greenhouse Gauges, for the Years 1846-1849. Observatory Gauge. Garden Gauge. Greenhouse Gauge. Month. 1846. 1847. 1848. 1849. 1846. 1847. 1848. 1846. 1847. 1848. in. in. in. in. in. in. in. in. in. in. in. Jan. 1-901 | 0-624 | 1-166 | 2-775 1-95 0-70 0-95 1-59 0-67 0-85 2-00 Feb. || 1-827 | 0-484 | 3-780 1-305 1-57 0-52 3-68 1-14 0.44 3-18 0-70 March 2-293 | 0-330 | 3-350 | 0-929 2-17 0-44 3-29 1-61 0-29 2-79 0-78 April 2:272 | 1-201 | 1-028 | 2-480 || 1-92 1-16 1:05 | 1-68 0-81 0-80 1-74 May 2:975 | 4-335 | 0-350 | 2-831 | 2-82 4-16 0-53 || 2-45 3-46 0-46 2-46 | June 2:761 | 1-970 | 3-826 | 2-379 | 1-86 3-67 | July 7:124 | 2-099 | 1-294 | 2-383 3:27 1-40 5-43 3-09 0-95 1-98 Aug. 4-738 | 1-035 | 3-223 | 2.547 | 4-69 1-08 2-60 4-34 0-87 2-32 2-12 Sept. 4-586 | 1-375 | 1-182 | 1-973 | 4-37 1-24 1-42 4-14 1-01 1-14 1-57 to on on nr ow _ Oct. 3-506 | 2-778 | 4-152 | 2-417 3-27 2-31 3-72 || 2.92 2-10 3-30 2-15 Noy. 2:054 | 1-839 | 2-252 | 1-309 | 1-88 1:71 | Gauge | 1-24 1-38 1-80 0-95 Dec. 1-817 | 4-006 | 1-627 | 2-000 | 1-95 3-21 | broken.) 1-15 2-95 1-20 1-46 Sums | 37-854 | 22.076 | 27-230 pene 34-45 | 21-66 Norr.—The Tables in the preceding pages have been formed in the manner already described in the volume for 1844. MAKERS TOUN MAGNE AE C OBSERVATORY... rare z. Royal SoeSians. Ldin Vol. XIX aS 20 30 40 FEET WAT Tohnston Se Term-Day Magneti cal Observations. January 22,23:1845. ie i os | | Beaoe t t a PEER x i | cI at | ! i a S i r : : | = H iS t i i T isin ia 1 i £ HI EEEEEE i + ha - Q S : i it A t ra i fe x | Co Bert ceaseeatcatets : i . § t CR it mel ims | H Tt i] [EI ij ECE EEE as a6 ae ee ‘ls bose | PEt £ a jajste Soiete los sb Tat falelat { fat a ial aC se aE 1 ae =e x SI 2 y 23 che 3 a B 8 a3. 3 3 a j & <1 — . “lee U21Z BUI 29 purus ug? JOLELOZILE FT purus fag POPPA : LJ io Curves indicate decreasing westerly declinalien andre. Ascending 1845. . aber en ruary THD 1 erm—Day Magnetical Observ. Hakeratoron Diservations - on 28> Lites 20% 194 J5* res 1crea a ves tndwule te dec i on imal I : CI | By FT T 1 {I - fle} f a] | = | T | el a | it i - 4 Sais Sle ststa| ie { i] Ino NIL ia tI T H 5. + + tulad t of ms bs HEH oi Tet a 1 x jae E i - ES | = sed seueuereeeaeea taneerez= { 1} : | | 1 “ES Soe EEESEES sagegeseeecs, I i | T jee ie noe +: { re t ! ISOS | { Be DaSaoe L. - ——- EEE SS Sie “oe ES : Hel I im eet Ty f | sag geetassnseeess seers ggg gseseee9 (see iH Fa r I is PERE EEE! : Pree try } - B IG et ~ E rl 7 : IE et Ss Gaae ttt | He FH - eet 1 Bs : = | > | 4 i rH CI siete] Eel far i] 1 Err LH D ie} 1 Gow Mean 171g DUI SPEER EEE eer pene aes puto ua gf UsIy, YopreozaLo FT {| |_| a quewo ung 3 72973-¢4 s tae Lien a ag westerly declen PO LSCR: ay Sy 2AL1845. 23 ons. April €) —Day Magnetical Observati Term Makerstour Vbservations » iz heme hie + Slater folafaal eel ata Seater rela ol te eee PEE 1 4 ws S alg) Se mee es UPVGRIOPIO Gaus lag VPLLOZLLO TT Ic J a) 3 3 $8 a » Quad fuiog POPTDLIAY ro sing force. 1edle KECEOSRG westerly Aecltnaen ANAL, S TEE ra Re far TH ch ma Beoa 1 i fs | | = t q 4 rT ii [anjah ra Via 1 1 | i ro r | 1 4 i | | j } yo i Sag A Sa N ] S Va | N | x xs | N | : d S | a a Do 1S = SS : S = nS | gig x y 12] a) & => dX i lof xs | = ee | a £ =I x 4 3 oe z S x a a | —~ . = | g 2 = : S a YO) : : SS 2 = S N ive SS {=| = St 4 s S is q | | NI é *.| i S | { 2 Be 8 ee 8 S BS aa i . y 3 LT ECE rc iets me ; 2 tT Eee HE EEE EAH] E Bs | Z ~ 3 = ze > o > o . | a ae ae i 2 20S ad 2 UPIZDUIZIAT purrwuad ie), D JOLMIZM«A ET purus lena LPPVLI F ei: SG r T =H jaeooao FS 8 { { ia I coo tet maa = f t rt | I t a a + a] 2H | oH : R aa | al t T i Pls mo i a i i S | Seuadessee! | b sls SE: | i * } a he sot i aS | i | | x : ry Sol it : } S y lo a x | tt f H NI | a } 2 roy Hoe | 8 | oo im it ee | a eee ae rH {s | g res | S| 5 a ee | Fs R 4 5 1 aufas } 2 = ia f N 2 | im a is pS e HH “a : H |§ ee gS & 2 3 |= t S : Hii a | F : + R } rs . | : 5 = { 1 i i 4 1 LO 4 t Poeeeet Loot ; S| 8) EERSEEE RECEP TTR aEr ror if [ I: tat 3) apo ietaperml SS JQeeeScenene i faa { | a a a a a Me “lg £ 2779 DU1J 9. purus ula? QOLLODILO TT puruagueag por1pLI4 4 . . Hakerstowr Observations . Gal Peay Mean Timejix Hs 2s 16% Term—Day Mapneti cal Observations. July 23,24:1845. Teh: LS 2 194 LES ifs, 223 ah oe ie 28 ap 2 td oe tl us oy At Jay PERE FG nal Ty q | [iP SSI ee lea elie SEER ere al noe Lt pel L — = = ++} to —|-4 ~ Ht 44] SS i ie i fe es ee i } tt aot! Beet ooeoel BEECH PEEL REE EeCHt 1 PEPE Eee EERE EEE EELS PELE EE -EEEEL EEE EEE EEE f sUeBEEEUat : ao c | : l | bs | | js a ry C HOMIDSGReIr ason et IC al S a t Teslonte| iat + E yy, I 5 im C N 1 jal E a i ijl |ete lela ele ELEN lal slale Bisimiatwlatsl a alai@ C| th a | LI seer seetiasttt : Nar seeeceas meade : Babe ~ al f - 37 ae 5 PRE EEE | E 8 fy i i | eel Ht Ht eIn il ci ia HEE fd oI elerers I} EEE 1 Th | ae | Bee aa aes | ue : cla a | Pt EI Oo mt Ia id 1 na im { IE it t i a ELH f [ tt | ECE Hl 4 = . | peedaret ss saaseta! : ace R it Pein Baaeeue a HM || : H BEER CEE EEE eee PE EEeE EE E A sears N ae Oooo jalelalelal [ E c \ t { a ial fi T +t All ae 8 oe | = i +t N i i a S| eee EEE : | A H 3 beter E (alte | q 108 es | ‘ ELH Tt E NS es a r | I t agi cI cl aI I [ | a0 ae roo 535} A - HH i a PEE EEEECE iy CEEELEEEt EEE EE i | i 30 r rr [ IC x ae PEE To ry _ sa Sls F aa Ett : paaal 8 4 co naan ial t 4 io © : aus H & 520 IE alata i] aa L S z] it at al CI | aoe Bale gee H+ jai : i | SE a S loo Ht PH Beau > +4 ‘al i} oo oo + = R : Ei eI ii x . i Lact 2 PR ASELEEE Baeeal BEELER The ee ~ LU Jt — bo [esl i ie Ee fa Soar i Hi 4 4 aoe i HEE 5 C cH o|-1 ae | H+ a aoe | LI} b +++ 4 ro H Boe H Se EE SEE EEE EEE ER ECE EEE ECE EERE eae ECE alatefeta | E Ghtingen \ Mt We ZT i a ZZ) a 75! Ts a 78> TH 208 De 27 238 as TE 2 BP am oF oS 7 BP a 10 lean Lime £4 Re ee Ascending CHV tndicate decreasing westerly declination and (nereasing far Ce. Plato LX, 1845_ Term-Day Magnetical Observations. Cugust 29530 7” « Wakerstour Observations - Gintn is wht Us Mean “+ y ia aoe ; PEE cls atabatalaa Be 5 ooh a BE | = i | | eI ai | |_| eislaig + sleeiaas! zl mt to ‘ i a Se S 5 3 > = > = Pose <2 ee Sa) eee ees ees 2 UTIPPUI LIA pususg ua? POLLO “ayn3s yous au PH Pueu fay PPPVLIA 50, 734 Tae Ws Gbttingen \M? anti Ascending Curves tndicate AECPOUSUT westerly declinalic wan't NETCONG fOTCE ve ae = ey I= { ia! I 4 ! sagaau ree saameee ui = i a I n oS in u fotetetetata meals q ; Tect I+ iB | ai Tt i ae i mt 1 i [- | ae Ine EI im = ol ! | Lies a eal iz me ana FEE | - Bae ai rt ; a y = ial an s sea oe F aan ia = _] * Al T |e. ott i i 2 f a { Sresdaivetzseest se? AMNITTITAL | ta 10s 4 i ° | 4 f EE | Senso 1 s a Tf [ 1 f is Gasce>J00 se Seeeeeees An : : ‘ ] 4 ae a Cee 7 be N a a f° i [ I E au z Talal . 3! = =| f Hl i i bry ) al ENS| 8 a oie ea, || S a i faba | ig = r- = x al ne o imi T iS A eo) rep i t x a) { \ 7 NY y, | I iN ey 2 | ea: cee | AN g Re vs 4 ; Y st t lz t t N mE =f t x tb ie man feet T = ely s eee N= | e iE 8 Boe | | B ane ep | | ret S BI S | ; Tt t S os S Sn] 1 ; s 1s = ert i t + { jot | Fa Meet set i < | a | Sige AN x | Soy To oes | 3 i eet i IE S 5 Fal i T i 2 oi { i eee! S Ep 1 Het T iS i: Se |S = SEC LeEe f x | 2 : sour eeeeecs| || A z EEE t t poe S / ¢ ~ & al = a ia oa i CEE & 7 : | {a fafeahal i‘ = pit i { | ial 5 ai Petit t qo ao aaoeo Bue Er | aeeee ; — § = - - meee oy ] HH i +t AFH | 1 =a f ac tt s t r Ie | 5 = PEs c i Bie iotet Coot . De eT = | moi cot 8 } RS i s - in T =| f , Biss | | [ | t 5 x i ha) r i . | A sseceeaan § : T T ale q i | |] E Z Ht - { i [4 It ial L. aS t x imal Cet | ia t - a aS T a ry] t ; j i EEE im im Baan od J r 3) sao Et poe i shaft stelehe EES 4 z f t be Hien ET a a at er ; o > ; S de ; a a | BE : MPV PIAZIICT pours) QO MOZILD FT puouagues, QD pRP1p-L4 P : “ayHOS JOMSN sy J PE | Ree = ———— ———————tti‘i‘“‘CS;Cé*SP xT. Plato. 1845. etical Observations. October 22,23 Term—Day Ma, bsermazions . » Waks sitar 103) MDD PIAD IAC Z PUBUIGF MEL) POMONA LT (OT CE. ae Zod COWL AM. Asecending Curves indicate decreasing westerly declina 7 TT. Plate, A D5c0H dng Curves trdrcate Aecroastyg westerly dectinaticn and eres force, ey: Magne tical Observations. (Lovember 28,29: 1845. Observations ~ Maherstouse UMAVGPUAZII CT fe? Ua ued, ? TUOMALA, ET yuouaduen, DQ PPP 44 st ou 845. g westerly dceclinalicn Gnbinereast YU fore’. estndieate MECHest?! we a *” ; cs Term—Day Magnetical Observations. December 24,25:1 a ee 4 ia i LC { s i i | | {| ( : } | HE {- { < i ia i t | 4G Ti R } S| Sesser co =o S| EY 4 AEH ] HH i t i ! | Bae! ‘ a COCCHEEEESEEE EE EEE EEE BEE EEE HE : =| SI bot FI IE IMEI IE eli t i i ae a 5 ie es aS 15) ea 3 pas == Spe Z 5 B ¢ * ze 2217 PUIDIANT PUPUIGF ULI) YD MIZMO LT pursusfuag porta SEL) AM PM AM — The /— =) an Piles Seren 6 7 DSS WN OS LA a p+# 10 2 2 2 3 ¢ 5 @ CEO IN LO) T DIURNAL VARIATION OF MAGNETIC DECLINATION AT MAKERSTOUN 1843-1846. Trans. Roy. Soc. Edin. Vol. XTX Fart Il. Plated, OS ny ay 1 et eels 1 eds SD GP eed eon Positive Ordinates indicate increasing Westerly Declination, Scale, 1 Div, = 2 minutes. “Mean of undisturbed days. 2 Mean of all, 2" DIURNAL VARIATIONS OF THE HORIZONTAL COMPONENT OF MAGNETIC FORCE AT MAKERSTOUN 1845 —1846. i Trans Roy. Soc. Edin. Vol XIX. Lartil. Plate ll. AM PM Mr \ Dy) >) IEA 2 5 + 5 6 7 8 DELO ILO, Dh iF oh 4 D 6 LID ON SOT AIZ IT 2 3 us oO 6 7 8B 9 iO HW oO Dec. = Feb, Mean Mar._ Apr. ai Positive Ordinates indicate increasing Horizontal Force. Scale, 1 Div.= 0-000#, Hor: Force =1. —~~/ ~ Mean of all. we Mean of undisturbed days. } : Eng@ by GeaAteman wee hie dy * DIURNAL VARIATIONS OF THE VERTICAL COMPONENT OF MAGNETIC FORCE AT MAKERSTOUN 1843 —1846. Trans Roy. Soc. Edin. Vol. XTX, Part Il. Plate IML 6 | CaSO RIOR Tae, ILO TO) TB SO A2 Dec._ Feb. =f. Seale, 1 Dip. = 0:0001; Vert. Force Positive Ordinates indicate increasing Vertical Force. re so Mean of undisturbed days. ~~ \— Mean of all. Eng by Geo. Aikman * Ai ee * DS oeamee ire pag sector Aone rng, 3 z Ren ll ae I | Bet 5h ba i DIURNAL VARIATIONS OF MAGNETIC DIP AT MAKERSTOUN 1843-1846. Trans. Roy. Soc, Edin. Vol_ XTX. Part IL. Plate IV. m SSS AM PM AM —— J Y, ~ LEE Ti BB BO ENG ES ASS SOP TDS TE ON TAD EAS OO ES CN LN a OS 1 ES Sy Lay A” NEMEC a ome Ns Se TNs DE) j ] mae Tapes reales are a en re = — oa tL = ~. = Negative Ordinates indicate increasing Dip. Scale, 1 Dw, =O-+ minutes. —7~Y/ \ Mean of all. 0%"... Mean of undisturbed days. ae Fo ay a Eng" ty Gea Aikman ure a Mine Ae r Re NOL asco me SR! kK 3 > 5 Sipe ines eens : 5 Nigles| = | 2 eae : | § | | | 10 3 Ww | = + Sis | a) CC RS ya IS oS i | A \ $y = Qed 7 ~ Ht | i] rN | , So = Seta : ey Sleek 7 | eS oF = ; ) = : Be |e sl | 4 l : | | | = : i} = ‘I | | s S = : | a lak | 8 S = al 4 je) 2 | : | nn ‘ 2 s : i ) te = ~ --| a |e ree icate 2 In i : E { +} | a x» | Z = ea ca S & \ N S —: eb ig ee gach ” J i t : 3 ; * tere re THE MAGNETIC ELEMENTS AT MAKERSTOUN 1843 - 1846. OF NUAL VARIATIONS = AN Trans, Roy. Soc. Edin Val. XIX, Plate VL. June Apr. Mar. Seb, Dee. Oct, Many Mar. —_Apr: Feb. Jan. May ar i Jan. ] | | eee Nov. Sept. uy. June July =0' 4 vision e+ | jo aes =0'2 0:0002 | Seale 1 di Declination | i | T | \Scale 1 division | Seale 1 div, HF| 1 | | | pcan | | | Seale 1 div. 000004 I EE = De Seale 1 dir | Total Force | | Annual Motions Scale 1 diviston = 0/02 eS S| S§ SS QA | | +) i 4 ' s yh wha WS Fat a Le wel i + vg Fey VL. EEDLE Trans. Roy. Soc Ldin. Vol. XTX. PartIL. Plate =(5}¢ 7 . MAKERSTOUN 184 - DIURNAL MOTIONS OF THE NORTH END OF A FREELY SUSPENDED DIPPING N | | Hee Sais al zi EB i = | 3 pay + =e] erates i a 3S atl = — Re | 3S is \ S ads \ Ss Sone > S fo | ee | 8 3 = 5 Is 3 S S SF tt s = SS S Sra E S [ae = s | : S ; = bee eS S y S WS * = x —"h ESS. rae > JIN Si] Rs Ss) = 43 fs —-1- Ss s Sh He § N all ial S Ss i > | oe — ae eS 8 ay NY a il j oeeeete as ; ra: DATE tire BED a, Sass ES Zs aS mae e SE gee oe oe aaa ~, ve ne ese eS fi ae, me aa, < aay SENSE hia = oe oot re cere are ¥ eee : CS tt sa Evia a Cane oes ot e pone Sw