Origin of Thunder Storms.

Physics without Apparatus.--Manufacture of illuminating
gas.--Elasticity of bodies. 2 figures.

Scientific Amusements.--Dance of electrified puppets.--Silhouette
portraits. 2 figures.

A Sunshine Recorder. 2 figures.

VI. MEDICINE, HYGIENE, ETC.--How Cholera is Spread.

Sulphurous Acid and Sulphide of Carbon as Disinfecting
Agents.--Methods of burning the same.

VII. MISCELLANEOUS.--Improvised Toys.--With numerous illustrations.

The AEolian Harp.--Kircher's harp, made in 1558.--Frost and
Kastner's harp.--Manner of making the harps. 4 figures.

How to Break a Cord with the Hands. 1 figure.

An Aquatic Velocipede for Duck Hunting. 2 engravings.

Skeleton of a Bear Found in a Cave in Styria, Austria.

VIII. BIOGRAPHY.--Theodor Billroth, Prof, of Surgery at Vienna.--With
portrait.

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ACKNOWLEDGMENT.

The illustrations and descriptions we give this week, entitled "How to
Break a Cord," "Prestidigitation," "Circle Divider," "Sulphurous Acid,"
"Production of Gas," "Aquatic Velocipede," "Several Toys," "Scientific
Amusements," are from our excellent contemporary _La Nature_.

* * * * *

THEODOR BILLROTH, PROFESSOR OF SURGERY AT VIENNA.

The well known surgeon, Theodor Billroth, was born on the island of Ruegen
in 1829. He showed great talent and liking for music, and it was the wish
of his father, who was a minister, that he should cultivate this taste
and become an artist; but the great masters of medicine, Johannes
Mueller, Meckel v. Hemsbach, R. Wagner, Traube, and Schoenlein, who were
Billroth's instructors at Greifswald, Goettingen, and Berlin, discovered
his great talent for surgery and medicine, and induced him to adopt this
profession. It was particularly the late Prof. Baum who influenced
Billroth to make surgery a special study, and he was Billroth's first
special instructor.

In 1852 Billroth received his degree as doctor at the University of
Berlin. After traveling for one year, and spending part of his time in
Vienna and Paris, he was appointed assistant in the clinique of B. von
Langenbeck, Berlin. At this time he published his works on pathological
histology ("Microscopic Studies on the Structure of Diseased Human
Tissues") which made him so well known that he was appointed a professor
of pat