I HAVE lately obtained and read “Schellen's Spectrum Analysis,” translated by the Misses Lassell, and edited by Mr. Huggins, and feel at length constrained to dissent from a statement which I there find—in this the present standard work on the subject—distinctly and repeatedly made, as I have seen it made elsewhere before, a statement belief in which has tended and must always tend to deter many from prosecuting independently a most interesting study. I refer to the passage beginning “The Possibility of Observing” (p. 382) to end of paragraph, italicising the words “ordinary” in 1. 7 of p. 383 ‘by increasing the number of prisms” three lines below, “highly dispersive power” in line 22.] The italics are mine, and are intended to indicate that to which I object, not that the particular passages in which they occur are explicitly incorrect, but that they implicitly convey the incorrect notion, that the “highly dispersive power” is essential to the primary success of the observation” of the lines of the prominences in bright sunshine.”