298 W. Gibbs on the measurement of wave-lengths. 
Art. XXXI.—On the measurement of wave-lengths by the 
method of comparison. Abstract of a paper read before the 
National Academy of Sciences, Aug. 16, 1867 ;-by Wotcort 
Gisss, M.D., Rumford Professor in Harvard University. 
more convenient and expeditious than that of least squares. 
The relation between the scale-numbers and wave-lengths 18 
given by an expression of the form 
A=a+t+bk+ck?+dk?, &. 
g them, as before, so as to correspond wit 
y Angstrom for Fraunhofer’s line D. As 
each group, 
venth eight, 
th seven measu 
| ae 5 
te. 
