In the second article Dr. Th. Lipps discusses some mooted questions of optics. The first part of the article is a reply to Schwarz’s criticism in the preceding number of the _Zeitschrift_. The second part is a review of Franz Brentano’s explanation of the optical paradox, discussed in the second paragraph of this notice. Lipps declares, that, though there is some truth in Brentano’s explanation, it is nevertheless an error to believe that acute angles, _as such_, are overestimated, and obtuse angles, as such, are underestimated. On the contrary, every time such errors in estimation occur, there exist particular reasons for it, the character of which renders the attempt impossible to derive the estimation of distance directly from the estimation of angles. Lipps supports his position by actual facts. His chief and most philosophical remark is, that it is a perilous and improper thing to do to explain isolated optical illusions by isolated and independent hypotheses; optical illusions are not exceptions: they constitute a class of phenomena in themselves, and they should be considered in their natural and logical connection. (Hamburg and Leipsic: Leopold Voss.). μκρκ. VIERTELJAHRSSCHRIFT FÜR WISSENSCHAFTLICHE PHILOSOPHIE. Vol. XVI. No. 3. UEBER REAL- UND BEZIEHUNGS-URTHEILE. By _J. v. Kries_. WAS IST LOGIK? By _A. Voigt_. ZUR PSYCHOLOGIE DER LANDSCHAFT. By _R. Wlassak_. DES NIC. TETENS STELLUNG IN DER GESCHICHTE DER PHILOSOPHIE. By _M. Dessoir_. The articles of this magazine are usually very rigorous and learned; and the contents of the present number are in keeping with its reputation. Prof. J. v. Kries discusses in an essay, evoked by the recent articles of Riehl, the subject of “real and relational judgments”; his object is to establish a classification, and display the logical connection, of judgments generally. Real judgments are predications concerning reality or actual facts; relational judgments predicate simple relations of concepts, etc. The first requisite of a scientific exactness of thought, says Kries, is the distinction and determination in any given case of judgments which are real and judgments which are relational. In the second article, which is long and exhaustive, Dr. Voigt endeavors to determine the characters and functions of the different kinds of logic. In view of the great prominence into which algebraical logic of late years has come, this article is one of considerable interest. Voigt defines the pretensions and powers of the two opposing systems of philosophical and algebraical logic, and attempts to set forth the justification of each. Voigt, as opposed to Husserl, cordially recommends the study of algebraical logic to philosophers, that both disciplines may profit by the intercourse. (Leipsic: O. R. Reisland.) μκρκ.