# Page:Popular Science Monthly Volume 4.djvu/605

587
FACIAL ANGLE.

we have been describing are as follows, and we give them that the reader, when next traveling upon an English line of railroad and passing a signal-box, may give a passing thought of thanks to the inventor of the "block" system, and the gentleman who framed these rules, Mr. William Henry Preece, of the Institute of Civil Engineers, and to the individual, let us hope, who follows them closely—the signal-man:

INSTRUCTIONS.
1. No train or engine is to be allowed to pass your box unless the electric signal for the section into which it is about to proceed stands at all clear.

2. When a train has entered the section of line which you have protected (under Rule 4), you will signal to the next station, two beats on the bell twice, to signify "Train coming; be ready."

3. On the approach or arrival of the train or engine at your box, you will, provided the electric signal stands at all clear, at once signal it on the bell to the next station in advance, thus:

 If a passenger-train﻿.﻿.﻿. by 2 beats " goods-train﻿.﻿.﻿.﻿.﻿. " 3 " " special or engine﻿.﻿.﻿. " 4 "

4. This signal will be acknowledged by the corresponding station, by throwing his switch-handle over to "on," thereby placing the electric signal at your station at danger, and protecting the line from any train following that already in the section.

5. You will acknowledge this signal by returning one beat of the bell.

6. On the arrival of the ${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$DownUp${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \end{matrix}}\right\}\,}}$ train at ${\displaystyle \scriptstyle {\left\{{\begin{matrix}\ \end{matrix}}\right.}}$${\displaystyle {\overline {\underline {\qquad \qquad \atop \qquad \qquad }}}}$${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \end{matrix}}\right\}\,}}$, the signal-man at that station will pull his switch-handle over to off, thereby removing your danger-signal, intimating the arrival of the train and clearing the line.

7. This you will acknowledge by one beat on the bell.

8. In case any obstruction exists upon the line to necessitate its being blocked, give five sharp beats on the bell (which must be repeated), and raise the electric signal to Danger, which must be maintained as long as the obstruction lasts.

9. No signal is to be considered complete until it has been acknowledged.

I beg leave to state that this article is written without being at all acquainted with the system of signaling on American lines of railroad, so that I am unable to say how far our own bears comparison with the English system.

 THE FACIAL ANGLE.
By RANSOM DEXTER, A. M., M. D.,

PROFESSOR OF ZOOLOGY AND PHYSIOLOGY IN THE UNIVERSITY OF CHICAGO.

THE methods of estimating the facial angle hitherto adopted by naturalists are all mere modifications of that proposed by Peter Camper, and consist in describing an angle with one line passing along the base of the skull, intersected by another which passes from the anterior portion of the upper jaw over the forehead.

Prof. Owen's definition is: "If a line be drawn from the occipital condyle along the floor of the nostrils, and be intersected by a second,