Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1897-08-06
MARVELLOUS MACHINE
ITS INVENTOR DESCRIBES ITS
WONDERS IN DETAIL.
SdAYES ROCK SIXTY INCHES SQUARE.
IL Cuts Slices to n Tbinness of One
One Hundrcdth of an Inch-Thc
Work of Many Years study-A Eoon
to the Scientist and Lapidary.
(correspondenee Of the pIspateh.l

a machine that would slice rock. While
these have been practically true, here.
Tor the first time is given the authentic
and detailed story OF what is certainly
one Of the most remarkable inventions Of
the century.
| The inventor is Professor William 3.
Dwight. Of the Department Of Natural
! History Of Vassar College. His machine
VIII slice rock sixty inches square TO a
thinness Of 1-1OO Of an inch, and the
cutting will be as perfect as II the OBJ
jet wero butter and the rock cutter a
keen-edged knife. The following Is Pro-
! fessor Dwights description OF his own
machine
/ THE object OF this article is to explain
in popular language the general charac-
! ter and work Of what is at least ore Of
| the latest and more perfect machines
/ for the cutting OF minerals, rock frag-
ments. either for scientific or Iapldary
purposes. \ few preliminary explana-
| lions will be advisable.
First. As 10 the meaning OF the word
cutting as applied 10 this machine.
ho SD-tdi4tu anu NfONElt -talleQ CUT
| ling Of gems In the lapidary work Of
! jewelry. as the cutting OF diamonds is
really no cutting at all. What is called
cutting In such cases Is really grind
! ing preceded I'm some cases by the
splitting or Of fragments by the blows
OF steel tools. This grinding IS effected
either by such hard powders as emery
carborundum, or diamond powder, or by
rubbing against some hard, solid surface
(as by rubbing one diamond against an
other diamond).
True cutting OF stone Is effected either
by the edge Of a revolving metalling
cutting disk. or by an Oscillating metal
lie strip or wire, fed or treated with an
abrasive powder. the best OF which Is
diamond powder. This cutting is prac-
tised by lapidaries In cutting slips OF or
namental stone. as for canoes. This
'petrotome' has no concern with the So
called cutting I'm its hrst mentioned
sense; it can hardly be OF any assistance
TO lapidaries in the cutting OF small
gems. The work which it does is essen
TALLY one OF true cutting or saving OF
mineral substances by a properly pre-
pared thin cutting edge. There are
grinding and polishing wheels. however,
connected with tho machine used in pre-
pairing or finishing it's work As will be
shown hereafter, 1t can be of Importance
to lapidaries I'm it's work OF true cutting.
"A misrepresentation has also arisen
from the use Of the title 'rOck-Cutting
machine leading even TO the absurd as
sertiOn In some newspapers that it has
been used in cutting rocks containing
gold by the ton, whereas, piece of
mineral as large as a mans head would
be an unusually large piece for this
kind Of cutting. The fact IS, that where
as the term rock both In popular
language and in general scientific usage,
refers to large masses of mineral mat
ter on the other hand it Is the only
general term available in lithology for
any mineral substance which is Il com
ponent of the great masses Of the earth's
crust and generally mixture Of mineral
species In this latter sense there l. no
reference to size. and any small piece OF
such material is called rock TO dis
tinguish IL from "a simple mineral which
does not compose crustal masses.
"a rock-cutting machine in a geologi-
cal laboratory is. therefore, one at least
capable Of cutting small pieces OF rock
substance. An explanation is next IN
order as to the objects sought 10 be ac-
complished by this machine in its scien-
tiGc uses. The value in lapidary work
will be treated later.
"In the present improved methods or
study in mineralogy and lithology-L e.
the study of the composition. structure,
origin. and alteration Of rocks-it is es-
sential that very thin sections shall be
made of minerals and Of rock sub
stances-so thin that most of the COM
ponent substances will be transparent
such sections may be from l-l50 to l-Z5D
or 1000 of an inch in thinness. BY cX-
aiming such sections under the COM
pound microscope, one can detect the
presence OF mineral species and Of phe-
nomena of structure, not otherwise readi-
ly, If at all, recognizable.
'In paleontol gy Che study of ancient
extinct life in the form Of fossils, it Is
often necessary to detect or ascertain the
structure Of fossils in rocks, either by in
spection of a cut and polished surface or
OF thin transparent sections for micro
scopic study. 1t is generally necessary 10
cut such surfaces or thin sections in den-
mite planes.
1T was because the so-called lapidary
iathes' generally used 10 accomplish these
results were Of too crude q character,
lacking any devices either for any ac-
curate adjustment of the specimen, or
for any adequate control Of the cutting
disk, especially for any specimens whose
section would be larger than a square |
inch Of surface. that the inventor was
compelled to devise his own machine ior
the purpose. He had no thought OF
any machine for general use, but
INTENDED it solely for personal use in his !
own laboratory in making many difficult !
sections, large and small. on large |
amount OF fossil-bearing specimens COL |
iected I'm his field Of explorations. After |
Oil. \. v,ta
il seemed TO take as the basis Of such a 1
machine the plan Of ono previously de-
y!scd By the eminent state Geocgist Of
New York state, Professor James Hall,
IN collaboration with his son. This ma
chine was in use at the State Museum In
Albany, and was capable Of cutting read
Nv very large sections, but its move
nents were very limited and there were
no arrangements for exact adjustment.
"As the machine here described is
very different affair from the 'lapidarys
athe' in having adjustments enabling IL
% aim at precision, il seemed TO deserve
/ distinctive name. An instrument which
AN cut with precision very thin slices
If soft organisms for biological study IS
allied a microtome AS this rock-cutter
s ftted to cut hard mineral substances
With considerable precision into thin
slices, IL mas SeeHeu dppIOpIldte 10 can
[ a 'petrotome.' since the Greek word
petros' means a piece of rock. The pc
,uliar features to which 1t owes its efii-
.iency are chiefly as follows:
Il A fixed plane of reference 10 which
III adjustments are referred.
"2 An object holder capable OF grasp
ne firmly any hand-specimen Of any
irregular shape while permitting lis ad-
ustment in any possible position.
'3. An adjustable cutter-guide capable
Z holdlna tie Thin cutting-disk accurafe-