VI. MEDICINE AND HYGIENE.--Filth Diseases in Rural Districts.--Showing why there is greater danger of poisoning from sewage in the country than in the city.--Several examples showing apparent causes and consequences.--How is the infection carried? 6450 The Physiology of Sleep.--Giving different theories 6451 A New Method for the Detection of Sugar in the Urine 6452 VII. MISCELLANEOUS.--Elephants Moving Timber at Moulmein, Burmah.--With engraving 6449 The Education of German Women 6449 Horse Medicine Bit.--With two engravings 6451 The Big Trees of California 6454 Science in Antiquity.--Heron's Pneumatic and compressing apparatus.--With two engravings 6450 * * * * * PATENTS. In connection with the +Scientific American+, Messrs. MUNN & CO. are Solicitors of American and Foreign Patents, have had 38 years' experience, and now have the largest establishment in the world. Patents are obtained on the best terms. A special notice is made in the +Scientific American+ of all Inventions patented through this Agency, with the name and residence of the Patentee. By the immense circulation thus given, public attention is directed to the merits of the new patent, and sales or introduction often easily effected. Any person who has made a new discovery or invention can ascertain, free of charge, whether a patent can probably be obtained by writing to MUNN & CO. We also send free our Hand Book about the Patent Laws. Patents, Caveats, Trade Marks, their costs, and how procured. Address: +MUNN & CO., 261 Broadway, New York.+ Branch Office, cor. F and 7th Sts., Washington, D. C. FOOTNOTES: [Footnote 1: Royal Institution of Great Britain.] [Footnote 2: _Comptes Rendus_ of the French Academy of Sciences.] [Footnote 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.] [Footnote 4: Ang. Guerout, in _La Lumiere Electrique_.] [Footnote 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.] [Footnote 6: Abstract of a paper read before the New York Academy of Sciences.] [Footnote 7: Trans. Am. Med. Ass'n, 1880.]