J. 0. F. Ziliner on a new Spectroscope. 59 
covery of spectrum analysis, presents the prospect of demon- 
strating this influence by the spectra of the stars. According 
to theory this influence must show itself in a small displace- 
ment of the lines of the spectrum. For example, for a mean 
velocity of the earth of four German miles per second, this 
displacement would amount to the tenth part of the distance 
separating the two sodium lines. “This value which is obtained 
in a very simple way from the velocity of light and the undu- 
lation-time of the rays corresponding to the sodium lines, has 
only quite lately been derived again by J. C. Maxwell, in agree- 
ment with earlier computations by F. Hisenlohr* and others. 
The amount to be observed of the displacement appeared 
? ait 
however, to Maxwell to be so small, that he closed his conside- 
tion of the lines), with the remark: “It cannot be determined 
by Spectroscopic observations with our present instruments, 
and need not be considered in the discussion of our observa- 
tions.” 
Huggins nevertheless in his most recent memoir,t of which 
the above mentioned investigations of Maxwell are an inte- 
gral part, attempted the solution of the problem in question 
by the use of a spectroscope with no less than five prisms, 
of which two are Amici’s, with two flint and three crown-glass 
prisms, 
he diminution of the light caused by so great a number of 
right lines from terrestrial sources of — with the analogous 
dark lines of stellar spectra. The latter have sometimes a dif- 
Heidelberg Transactions of the Phys. Med. Soc., vol. iii, p. 190. 
+ Phil. Tyan, 1868, p. 532. t Ibid., p. 535. 
