Show I THE CAUSING OF SUMMER By y t l P. P ls Copyright ht 1907 BOi A perpetually recurring question of or Interest to everybody Is that of or the nature of or the change which turns turne winter Into summer or orIca vice Ica versa intelligent people sometimes permit in disregarding or rejecting tho the explanation tion offered by b astronomy an explanation explanation nation which Is nevertheless perfectly per per- per per- perfectly sound and irrefutable la The Thc sun gun is I just now rapidly rising again from rom the Southern rn Hemisphere re and on the 1st of at March It will cross tho the equator and in the Northern Hemisphere Hem Hem- will begin to rise and bet et t north of or tho true ea east t and west points The gradual Increase o of temperature and the awakening awaken 1 of oC vegetable t ble fife in our in-our our part of oC the world will follow ollow from the i growing warmth of or the atmosphere and soil caused cl both by the higher Inclination of the sums rays s aun-'s rys and antI the the- Increasing length of ot time that It i-e- i mains mainI above above e tre horizon horizon ln In other words the excess as in length of or da day over night On the Ule 1st 1st of oC June Jun the tho summer solstice when the sun nun reaches Its its I northern declination the days will attain attain at- at tain their greatest and the nh nights their least length In the Northern Hemis Hemisphere I phere But Jut the heat will continue to accumulate for a month or Mix six weeks after aHel that date because aitho although the difference will be decreasing the tbt dove davs will continue to be longer than the nights night until the arr arrival al ot us the Autumnal Equinox September 22 an and the surface of ot the earth will receive recel by da day da- daa a greater quantity of or heat than timan it will radiate oft off by night Both of ot the causes above cause above mentioned operate together The sun aun being Ing higher high high- or er In the sky k tho same ot oC o its beams fall tall upon a smaller area of the earths earths' surface nil aril heat heet U ll more than when n lee Hie 8 aa as In winter and when con consequently th the same quantity of ot radiation Is to dis dis- distributed distributed over jover a greater mount Amount of oi surface Anybody can caD satisfy tt fy himself himself- in a mom moment nt of th the tho effect effect- oi o lh of ot a. a surface upon the amount of ot heat received by it Il by holding the back o of his hili hand first r t squarely before fore a tire or a hot lamp lampi ht and then without changing the the- thet distance t tance turnIng turning turn- turn In Ing It so that the rays ray fall tan v very ry slop slop- in I A 1 marked cooling e will b be noticed as U soon lOon as the surface of ot the hand is i S pre presented at a low angle to tho the impact o of the heat rays raya They come In straight parallel lines and no matter how crowded this may b bethe be be- bethe the number falling upon any given surface will depend upon the inclination Inclination tion of that surface to the direction of or th the ray rays This Tats 1 is graphically Illustrated Ih J figure n N I 1 t where we have haTe two lines linese of e y die the Ule name stamo JeD length b. b X A B Band and andA A C C. are presented pr ed at A steep slope slop to tb the rays and the other othu presented square to tp them The eye fiT perceives th the effect ot qt t once Th thing I In ire principle occurs when the site th suns sun's rays r reach hatch ch the earths earth's r 1 fi f surface at a low lo or a high angle Yet Yel this perfectly manifest fact which Ila plays s 's a chief part pait in producing the change of oL the seasons Is s frequently disputed The Phe cause other o of the time accumulation of ot- othe heat he producing t summer Is Illustrated Illus rated In figure ligure No 2 Here we see that while while- da day day- and night ate ale always equal on the equator they the vary yar greatly great great- ly in both the Northern and the Southern hemispheres We e have ha taken talen the state of things as it will be on the tho af of the time coming conning month of oC June Then Ihen the sun ut at noon will be only about seventeen and a half degrees south of or the zenith or overhead point and antI will rise In the northeast andset and andset set let In the northwest It will several bC be everal hours longer ions r above tho the horizon in ever every twenty twenty- hour four tour four period than It I Is below itIn it ft In other words the day ds will m be much longer than the night night about about six hours fumes longer day lasting fifteen hours and night nine hours In the figure a rough comparison of oC the the- length i of day ay and night Is lIS furnished furnished fur fur- by h the tho relative e lengths of oC the theto two t parts the dotted dolled line connecting th- th the places of or New of-New ew York r ar r n n n a a nee at midnight It will wIH be soon scon that as N York Is hi carried round by the earths earth's rotation it Is in much longer In Inthe Inthe inthe the sunlight than In the shadow Y A glance will also show sho that the relative length of ot the da day as compared compare compared com com- pare pared with the nl night ht increases Increase at all points on the earth north of oC New NewYork NewYork e York until when h n the polar circle Indicated d by a short dolled dotted line is reached the night disappears entire entire- ly Ty ald 1 Continuous day reigns around the tho North orth Pole In the Southern rn Hemisphere r the reverse reverse re re- verse n y occurs and there the days arc shorter than the nights Just as during our winter while at ai atthe atthe the Antar Antarctic Circle day a vanishes entirely Entirely entirely en en- and continuous nJ night ht reigns within circle around the South Po Pole to Sir Robert Ball has calculated 1 that IT rr th the t total Ul quantity of or heat received by the earth from the sun aun In tn a year be represented by then each hemisphere hem phere in tn turn will receive 29 of ot these th units during Its summer and during it its winter |