The sun., 1893-09-10
xorEs ON SCIENCE AND INDUSTRY

An account IL given OF some interesting OK.
periments conducted by the Societe de TouaRe
dc Ia Basse Seine ct de pOlse upon the River
Seine. which have eliminated In the con
struction Of q towboat OF large dimensions,
whose towing apparatus has been provided
with q number OF gnetized pulleye. In size
the main towing pulley IL but little over four
feet In diameter. It being simply q solenoid
whose soft iron coil is hsneed to
form the groove. the bottom Of which
is bronze ring with rubber joints to prevent
ss Tss 0 S% ns yo hs The SSos
great strength. and. besides the advantages Of
much greater one that the proper amount OF
adhesion is obtained with only three -gua arters
as a brake on the slack Of the chain SO that It
can be properly paid out
Referring to some OF the more valuable con :
illusions arrived at by recent astronomical re-
search. an English writer argues In favor OF
the theory that the stars. or many OF them. are
very similar to our own sun. this being clearly
shown from three considerations. One OF
these 10 their great intrinsic brilliancy COM
pared with their small apparent diameter. q
diameter so minute that the highest powers
OF the largest telescope fail to show them as
anything but mere points OF light with
out measurable magnitude: second, their
vast distance from the earth. dis
tance, SO great that the diameter Of tho
earth's orbit dwindles almost to a point
in comparis ison-this also accounting satisfac-
torily for tho first fact: and third the srectro-
scope-thpt unerring instrument Of research
many OF them is worry sim lar to that radiated
by the sun. Thus. their chemical and phys.
our central iuminnry. Trough the spectra Of
the red stars differ much from the solar spec
trum, these objects are comparatively rare.
forming exceptions TO the general rule.
1t has been nscertained 5y Prof. Kernot OF
Melbourne University. Australia, that the US
ually assumed weight OF 81 to 100 pounds
per square foot, produced by dense crowd Of
persons. may be largely exceeded. In an
actual trial n class of students averaging 1895
pounds each In weight were crowded In lobby
containing 1923 square feet, making an
average floor load OF 1347 pounds. room
still being left to place another man.
which would have brought up the loading to
Irish iaborers. averaging 145 pounds each.
measuring 81 square feet floor area. and the
load in this caso was about 147 pounds per
three laborors crowded into q hut feetby s feet
inches. load OF 142 pounds was produced.
with estimated room for two or three m en- ad-
ditional.
According to writer in Po,cer. engineers
should apply the steam engine indicator at
least once week. and some rig for reducing
the motion Of the piston should be available
which will admit OF easy attachment without
stopping the engine A unique arrangement
OF this kind has been introduced. which con-
sists Of light brass wheel which has two
dameters. the larger diameter being OF such
dimensions that the circumference will be one
halt the stroke Of the engine. and tho smaller
hsVRs Ing ,circumfersnce o5e'ha the length
Is attached to the cross. head. and q cord fr ON
the wheel Of smaller diameter leads to tho
hooked to an idler cord which passes over n
leading pulley to a wei ght. while the indicator
Of the wheel causes, the return motion after
eross-head; This RIG. asa permanent attach
proved satisfactory.
A Anut-tappinG machine has been contrived by
Rhode Island inventor which automatically
presents in succession a number OF nuts to the
tap. releases them from the holding jaws after
tapping. and pushes them on to the shank Of
the tap. and. whom the desired number OF nuts
has been tapped. the machine Is automatically
stopped. The apparatus Is described as hav-
Ing a longitudinally rotatahle tap and means
for driving the same. the combination with the
table. movably supported by frame in front Of
ssp and ad arm bs ena
the frame. There is a feed box secured to the
central forward portlon OF the table. and a Jaw
the box. the spring operated bar car'ying fin
gers supported in slide on the lower surface
pressure m @ by a rod piyoted to the bar. and to a
depending arm on the ,eole. being adapted to
be engaged by stop and rack secured to the
tween studs bel ow the table and having a
semicircular nlnion engaging with the rack.
and a rod connects the lower end OF the lever
with that OF the pvoted lever.
The example furnished by nature in the pro-
duction Of marble from chalk by water-the
latter percolating gradually and steadily
through the chalky deposits. dssolving the
chalk. particle by particle. and crystallizing 1t.
mountain pressure efreoting its charaote ristc
is now found may be the basis OF
similar results by resort
to chemical processes. Slices OF chalk
color path, staining them with tints
the same mineral stains answering this end as
are employed in nature. for instance. to pro:
duce the OF the TTeknown Il; and
plication is resorted to-, and. In a similar
manner. green. pink; black; and other color
placed In another bath. where they are hard
ened and crystal lied. coming out to all intents
and purposes real marble.
recent improvement in photography en-
ables the artist to overcome to a considerable
extent the difficulty OF preserving the natural
expression Of the sitter during the necessary
period Of exposure. 1t seems that. notwith-
standing this period has been greatly short
ened in various ways. particularly BY the
adoption to such an extent OF the magnesium
light. with its unique advantages, nervousness
Is SO prevalent among those who sit before