1 Royal Institution of Great Britain.

2 Comptes Rendus of the French Academy of Sciences.

3 It is often desirable to make one of the apertures twice the diameter of the rest; it causes a greater intensity to be given to one image, and that facilitates the calculation of time, while it furnishes points for the comparison of the movements of the lower limbs with those of the arms.

4 Ang. Guerout, in La Lumiere Electrique.

5 Abbe Moigno, in his treatise on telegraphy, assigns the date of 1838 to this publication; but Mr. Zetsche (d.c.) gives it as 1811. We shall consider the latter as the true date; for, in 1838, there was no reason for publishing Soemmering's memoir, and especially for proposing improvements in his apparatus.

6 Abstract of a paper read before the New York Academy of Sciences.

7 Trans. Am. Med. Ass'n, 1880.

8 In foetal syphilis it is assumed that the spermatozoa may be the carriers of the disease; but no microscropist has yet described a separate species of spermatozoon for such cases.

9 "The Philosophy of Mystery," London, 1841; cited by Hammond in his work on "Insanity."

10 See articles by Dr. Hammond in this journal for 1865 and in the "Journal of Psychological Medicine" for 1869, also his "Sleep and its Derangements," Philadelphia, 1872, and his "Treatise on Insanity," New York, 1883.

11 Yung, "Le sommeil normal et pathologique," Paris, 1883.

12 "LeÇons sur l'appareil vaso-moteur," t. ii., p. 154.

13 "Principles of Psychology," vol. i., pp. 88, 89.

14 "Les causes du sommeil," "Revue scientifique," t. xix.

15 Yung, op. cit.

16 Magnetic iron and pyrites in basic rocks; tin stone in granite and porphyry.

17 Ancient authors report cases of this kind.

18 The largest bronze statue of modern times is the "Bavaria" in Munich, which is 20 meters high and weighs 80 tons. It consists of 12 pieces and cost about a quarter of a million dollars.

19 When a bronze is remelted six times the percentage of tin is reduced to half the original (Dumas). The evaporation of the metal can be shown by holding a cold plate on it while melted. Tin is immediately deposited on it.

20 They usually made a copper and zinc alloy, but it is possible that they also understood the art of embedding the casting in zinc ore (calamine) and heating strongly, whereby the surface of the metal was "cemented" and colored.

21 On examining a broken surface of an antique mirror, it will be seen that only the outside is white. It is probable that the finished mirror was embedded in some arsenical substance and heated, which cemented and colored the surface.

22 Uchatius makes his famous hard bronze by cooling and hydraulic pressure. Bronzes with 8 to 12 per cent. of tin are most benefited by this process. Bronzes with very little tin in them are but little affected by chilling and hammering (Riche). Alloys that are hard already, such as bronzes rich in tin and phosphorus, become too brittle and useless by repeated hammering.

23 When a cast sheet of inelastic bronze or brass is hammered or rolled, it "feathers."

24 The Romans preferred to put in some bronze that had been repeatedly cast.

25 One piece was scarcely scratched by feldspar, another by quartz. The Greek and Roman weapons in the Berlin Museum were tested as to hardness by Dr. Von Dechend at the suggestion of the Director-General, Von Schone. All of them were scratched by fluorspar; there were no hard bronzes among them. If the races of classical antiquity were not acquainted with hard bronze, it is easy to see why they soon began to use iron, in contrast with the Semitic-Hamitic races.

26 Excrements were also much used by the alchemists and pharmacists of the middle ages.