144 PROGKESS IN ASTRONOMY. 



A. H. Newton, and other workers on those tiny celestial messengers 

 which give rise to the phenomena of '"'' falling" or '■■ shooting" stars. 



The magnificent displays of 1799, 1833, 1866, and, alas, that which 

 failed to come in 1899, we now know must be associated with Tempel's 

 comet. This is by no means the only case so far established. The 

 connection will in the future be closer still when the orbits of the 

 various swarms observed throughout the year shall l)e better known. 



Comets which attract public attention by their brightness and 

 grandeur of form are rather rare, and, in fact, only twenty -live 

 of such have been seen since 1800. We have, however, with the 

 great advance in instrumental equipment, l^een able to discover man}^ 

 which are scarcely visible to the naked eye, and this has swollen the 

 number of comets very considerably. In the seventeenth century we 

 find that only thirty-two were observed, while in the eighteenth this 

 number was more than doubled (seventy-two). This century more 

 than three hundred have been placed on record, which is practically 

 more than four times the number seen last centur3\ 



The last great comet visible any considerable time was that discov- 

 ered by Donati in 1858 and so carefully observed by Bond. It is 

 unfortunate that since the importance, in so many directions, of spec- 

 troscopic observations of comets has been recognized they have been 

 conspicuous by their absence. 



THE CONNECTION BETWEEN SOLAR AND TERRESTRIAL WEATHER. 



Everybody agrees that all the energy utilized on this planet of ours, 

 with the single exception of that supplied by the tides, comes from 

 the sun. We are all familiar with the changes due to the earth's daily 

 rotation, l)ringing us now on the side of our planet illuminated by the 

 sun, then plunging us into darkness. That changes of season must 

 necessarily follow from the earth's yearly journeA^ round the sun is 

 universally recognized. 



On the other hand, it is a modern idea that those solar phenomena 

 which prove to us considerable changes of temperature in the sun 

 itself ma}^ and, indeed, should, bo echoed by changes on our planet, 

 giving us thereb}^ an eleven-year period to be considered as well as a 

 year and a day. 



This response of the earth to solar changes was first observed in 

 the continuous records of those instruments which register for us the 

 earth's magnetism at any one place. The magnetic effects were 

 strongest when there were more spots, taking them as indicators of 

 solar changes. Lamont first, without knowing it, made this out at the 

 beginning of the latter half of the century (1851) from the Gottingen 

 observations of the daily range of the declination needle. Sabine, 

 the next year, not only announced the same cycle in the violence of 



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