PHYSICS OF THE GLOBE. 191 



at Buenos Ayres to an increase of 138 on Wolf's scale of 

 solar spottiness, and at Bahia Blanca to an increase of 193 

 on Wolf's scale. 



Fritz contributes to Peterraann's Mittkeilungen a memoir, 

 in his well-known exhaustive style, on the Periodical Changes 

 in the Lengths of Glaciers. A glacier is a very delicate 

 meteoroscope, and the changes in its volume and length, de- 

 pending upon a combination of several circumstances, enable 

 ns, as it were, to integrate the meteorological conditions of 

 the year. Professor Fritz suggests even that through them 

 we may find a new bond of connection between solar spots 

 and terrestrial meteorology; and, in fact, finds most remark- 

 able coincidences between the hundreds of cases that he has 

 collected and the dates of sun-spot maxima and minima. 

 With an increase of sun-spots comes an increase in the length 

 of the glacier. 



Perhaps the most interesting contribution to this subject 

 is that given by Professor H. Fritz in his study of the peri- 

 odicity of the rise and fall of the Nile, as recorded on the 

 nilometer of the island of Rhodes. He had at his disposal 

 only the record of the highest reading on the nilometer for 

 each year from 1825 to 1872, and he shows that these follow 

 Wolf's sun-spot numbers with most unexpected closeness. 

 The years of minimum sun-spots are nearly coincident with 

 the years of least rise in the Nile, thus confirming Meldrum's 

 results for the southern hemisphere. It is to be hoped that 

 it may become possible to similarly investigate the mean dis- 

 charge as well as the maximum heights of the Nile. That 

 this periodicity was known to the ancient Egyptian priests 

 is rendered plausible when Ave recall Joseph's prediction of 

 seven full and seven lean years, corresponding to the seven 

 years of high-water and low-water, and agreeing closely with 

 Fritz's table of periodicity. 



In Vol. XX. of the Vierteljahrsschri/t of the Natural His- 

 tory Association of Zurich, Fritz has an essay on the Longer 

 Periods of the Auroral Phenomena, in which, among other 

 things, he, as the first who, in 1863, fully demonstrated the 

 parallelism of sun-spots and auroras, very plainly protests 

 against having been ignored, but copied by Loomis in his 

 famous essay of 1866. In the present work, by a new and 

 improved method of analysis of a vastly larger collection of 



