Apprenticeship and professional teaching

Scientific

502

Notes and Cowwtents.

extreme

variations

in the quantities

sioned

by bacteria,

is of importance

to the hygienist.

of the

matter

two days

two-thirds

of ammonia,

organic

nitrous

[J. F. I., and

nitric

acids

The factthat was no longer revealed

occa-

in twentyby potas-

sium permanganate, and that the qualities of ammonia, nitrous and nitric acids, varied between zero and a relatively large gravity, shows that estimations of these substances are of value only when made on a water at the time it is delivered

for consumption.

W. H. G. -MISCELLANEOUS.

A~PKENTICESHIP the industries

,in the quality ber of select

AND

which

PROFESSIONAL

have

of labor.

TEAcHInc;.-Printing

is

among

the greatest

need of being raised and sustained was formerly an art practised by a small num-

What

workmen,

has now become a trade The multiplication production.

transformed by the requireof daily papers, magazines ments of quick and all classes of printed matter has resulted in a sensible lowering of the standard of workman’s skill. Efforts should be redoubled, not only that the artistic production cheap production industrial does not

of printing may not be endangered, but that may not fall below that degree of correctness

product should give satisfactory

maintain. results,

Apprenticeship, sometimes

the

the common, which every

as it is now master

regulated,

fails to do his duty,

sometimes the apprentice breaks his engagement as soon as a tirst degree of education insures his gaining a salary elsewhere. Often it is impossible in one work-shop to train a workman in different branches of the same work, and often the workmen themselves limit the number of apprentices, fearing the influence of their labor on the rate of wages. The French government has tried to remedy this evil by establishing special schools for industrial instruction

; still, many capitalists

prefer

to prepare,

under

recruits for their force of workmen. This plan has been out in M. Chaix’s professional school for young printers

their

own direction,

successfully carried in connection with

the central railroad printing-house in France. Applicants must be thirteen years of age, and prove that they have received primary instruction. The term of apprenticeship is four years. Beside practical instruction directed by

a foreman

instruction

for

each

in history,

of

edge necess?r?y for him when and incorrect copy containing languages. of books

the

geography,

specialties, the ancient

the apprentice receives and modern languages.

he may be called technical terms

upon to work or quotations

Outside of the regular courses, there are lectures, written for apprentices’ use, a library of appropriate

many helps also frequent medical

for moral education. visits, by a system

from from

ample Knowldifficult foreign

distributions works, and

Hygienic conditions are assured by of warm baths, and even by vacation

trips to the mountains or the sea for those in poor health. Especial precautions are taken to prevent risks in the use of machines. The apprentices are taught foresight and saving, and start bank accounts with the percentage which they receive on the result of their labor. 13~ training in dexterity, easy reading of manuscript, judicious use of characters and the intelligent disposition of tables of figures, they are led progressively to do productive work fat which

they

may

receive

;L

bounty

of from

ten to seventy

cents

a day.

;\fter

June,

Scien&jZ

1887.1

finishing

their

they

easily

Lbmments.

and

earn

from

$I to

503 a day.--&&.

$1.20

LEIL’ lu

C.

X Emour., /z@v, 1886.

Sot.

GRAPHICAL e

course

Notes

de@

TNTERPOLAToR.---In

Architetti

Italiani,

Roma,

the Anndi

della societal de&i

1, 1886, fax.

Anno

iv, a very

h..ppevi

ingenious

device is proposed and described by G. Torricelli, C. E., to divide the distances between level curves or soundings, on charts, in any number of equal parts,

FIG. I. for the interpolation of other The mean feature or scale. which

can

stretching

scale

be

stretched

the inventor

level curves or soundings, without using dividers of such device is a rubber-band graduated scale, to

more

accomplishes

to a pair of double

tongs

than

double its ordinary g the extremities

by securin

provided

with

ratchet,

length. This of the rubber

as shown

in -Eik. I,

but the simplest way of.accomplishing this, we think, would be to secure scale to a slide provided with a set screw, as shown in F
such evi-

1.. D’A. THE

OATMAN NIGHT-SIGNAL

night-signal lantern The common torch, used

for carrying

LAWEKN.-A

successful

test of the Oatman

was made recently by officers of the army and lighted with lard oil or turpentine, has heretofore

messages

at night

well as on shore, but the system lantern is so arranged by a simple

between has proved mechanical

far-off

stations,

on board

navy, been ship

as

untrustworthy. The Oatman device that flashes of light can

be shown as desired. These flashes correspond with the dash and the dot in the electric telegraph system-a long flash corresponding with the dash.