216 Dr Schuster. The last two total solar eclipses. [Nov. 18, 



of the equator two large rifts, forming what the Siamese in 1875 

 called fish-tails. In 1869, when the sun-spots had increased to 

 double their number, the form is entirely changed, and we have 

 now large polar rifts which extend as far as the equatorial rifts. 

 In 1870, when the sun-spots had just passed their maximum, it 

 would be difficult to trace any axis of symmetry. In 1871, when 

 the quantity of sun-spots was still large but' much smaller, the 

 polar extension was still great, yet there is a distinct axis of 

 symmetry. In 1874, when the quantity of sun-spots was reduced 

 to little more than in 1868, a reversal to the old shape is already 

 distinctly visible, and becomes more apparent in 1875. This last 

 year the general outline of the corona was very similar to that 

 of 1875. Whether this gradual change is accidental or really con- 

 nected with sun-spots it is too early to assert, but there can be no 

 doubt that the change exists. In trying to discover a reason for 

 such a remarkable connexion between the shape of the corona 

 and the quantity of sun-spots, some ideas forced themselves on 

 me, which, however unproven they may appear at present, are, as 

 far as I know, not contradicted by any facts. I have already men- 

 tioned that these long streamers which extend outwards from the 

 sun have to many observers suggested the idea of meteor streams. 

 The way these streamers are distributed shews that their orbits 

 must be very eccentric, and that in their perihelion passage they 

 must pass very near the sun. The great heat at that point, the 

 increased chances of mutual collision, and their entry into the 

 solar atmosphere, must cause many of them to fall into the sun. 

 The local increase of temperature caused by the fall must give 

 rise to currents on the surface of the sun, and may give rise to the 

 cyclones which we call sun-spots. Suppose now that these meteor 

 streams have a period so that every eleven years an increased 

 quantity of meteors passes the perihelion, we should observe 

 every eleven years an increased quantity of sun-spots, and at the 

 same time we should observe a difference in the shape of the 

 corona, which may well be of such a nature as is actually 

 observed. 



If I venture to bring this hypothesis forward it is only 

 because it shews the importance of the facts which may be 

 brought to light by eclipse observations. 



Dr Schuster also' exhibited to the Society Grant's small cal- 

 culating machine, for the multiplication of eight figures by eight 

 figures ; he explained its construction and compared it with the 

 well-known machine of Thomas de Colmar. Grant's machine is 

 much smaller than Thomas's, but does not perform subtraction 

 directly as is the case with the latter. 



