from Plans and the like Drawn to Scale.
Year: 1886

page_text: from Plans and the like Drawn to Scale.
I FRANCIS OBRÉ FERGUSON of Gothic Cottage Goldhawk Road Hammersmith
in the County of Middlesex Assistant Architect and Estate Agent do hereby
declare the nature of my invention for AN IMPROVED INSTRUMENT FOR ASCER-
TAINING LENGTHS AND DISTANCES FROM PLANS AND THE LIKE DRAWN TO SCALE
to be as follows:-
Within a circular metallic case divided into two parts the upper part being free
to revolve on the lower part and having on the top face a glass cover I provide a
suitable frame or pillar plate secured to the upper part of the case having on the
inner or plain portion angular spaces marked on which are indicated the values
of various scales such as are used by Architects Surveyors Engineers &c and also
containing a circular shaped recess or trough on the outer portion within which
I provide a number of ring like dials of thin metal superimposed and having
indicated on them graduated scales agreeing in their values with the various terins
marked on the plate Each of these dials is cut through in order that by means of
the engagement of a projection on the outer edge of the dial with a spring socket
piece on the case any dial may be brought by a revolution of the top case into
position for reading at the top of the pile and similarly returned to place by way
of certain short inclined planes placed at intervals round the circumference of the
recess Below the pillar plate I provide a drum on which is wound a chain one
end of which is fastened to the drum while the other end is free to pass through an
opening outside the case This chain-recoverable upon the drum by means of a
coil spring-when pulled out by revolving the drum operates a pair of hands or
pointers above the pillar plate one of which is geared to travel faster than the
other The method then of using the instrument is as follows When a line is to
be scaled or measured the dial of the proper scale value is brought to the surface
of the pile in position as described and the chain pulled out and applied to the line
to be measured The pointers traversing the dial indicating on it the correct
distance in two terms say of chains and links and also of feet and inches &c.
Dated this 15th day of Tonuow 1900

page_text: An Improved Instrument for Ascertaining Lengths and Distances
from Plans and the like Drawn to Scale.
I, FRANCIS OBRÉ FERGUSON of Gothic Cottage, Goldhawk Road, Hammersmith
in the county of Middlesex, Architect and Surveyor assisting in the Estate
Department of the London and North Western Railway Company, do hereby
declare the nature of my invention for AN IMPROVED INSTRUMENT FOR ASCER-
TAINING LENGTHS AND DISTANCES FROM PLANS AND THE LIKE DRAWN TO SCALE
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:-
The purpose for which this instrument is made is as follows, Architects Engineers
and Surveyors scales used for delineating surveys, plans drawings and such like
are represented in and divided into a certain number of chains feet and links or
feet and inches respectively as the case may be or into a certain number of parts
to each and every lineal inch.
It is intended to represent on each and every one of the dials the correct number
of relative parts in chains feet and links or feet and inches as the case may be and
as are contained in three lineal inches according to the scale required and which
will be indicated by the fast indicator and also to represent on the same dials the
number of parts or chains feet and links contained in twelve lineal inches and
which will be indicated by the slow indicator and which will be necessary to
simplify the reading of the dials, if therefore any length of the chain be pulled and
if more than three lineal inches both indicators must be referred to but if less than
three lineal inches in length be pulled the fast indicator will be sufficient to
represent on the dials the relative number of parts in terms of chains feet and links
or feet and inches as the case may be and as may be shewn on the dial according
to the scale used and as may be contained in such portion of three lineal inches
An example of a dial is shewn on the drawings set out to a scale of 44 feet to
an inch.
It is intended to represent on the dials the following scales, and such like which
are known and expressed in terms as follows:-
chain to 1 inch, 1 chain to one inch, 2 chains to 1 inch.
3 chains
4 chains
30
"
6
1 foot
"
"
'
4 feet
6 feet
"
وو
,
ths and
630
5
"
"">
"
"
"
"
"
2 feet
"
12
8
"
"
,
ور
"
"
..)
th scales also ordnance scales 500. 18, 1000, 1056, 5500, 10800,
Each, every, or any one of the above or others.
The instrument is contrived as follows a brass solid drum D is made to revolve

page_text: Through the centre of the drum's circumference is fixed a steel arbor A to one
end of which is fixed a toothed wheel H which causes two steel indicators I to
revolve by certain means to be hereafter described, one of these indicators revolves
at the same time as the drum and will make exactly the same number of revo-
lutions The second indicator is caused by a train of wheels and pinions W to be
hereafter described to revolve only once to twelve lineal inches of chain or four
revolutions of the drum. The result will be for each revolution of the drum
the fast indicator will represent in each revolution over the dials G to be hereafter
described exactly three lineal inches of chain the slow indicator will represent a
quarter of a revolution on the said dials and also equal to three inches of chain at
that point-The following revolution of the drum will represent six inches of
chain by the fast indicator and the slow indicator will make a half revolution.
Another revolution will represent nine inches of the chain by the fast indicator
and the slow indicator will make three quarters of a revolution Another revolution
and the last and both indicators will point exactly at zero from which point they
both started and will represent exactly twelve lineal inches of the chain.
The fast indicator will therefore represent on the dials any portion of three
lineal inches of chain and the slow indicator each and every three inches of the
chain or a part of or the whole length of same.
The instrument is circular on plan the main plate M of brass is about one
sixteenth of an inch in thickness and to the underside of which is attached trains
of wheels gearing with a wheel fixed to the arbor of the drum and also gearing
with a toothed rack L all to be more particularly described hereafter.
To the underside of the main plate is fixed two main pillars P at opposite sides
of the main plate.
To the underside of this main plate is also fixed a small pillar to which is fixed.
a thin piece of steel K required for a purpose hereafter described To the under-
side of this main plate are also fixed three pieces of steel or brass to act as guides
for the rack to be more particularly described hereafter.
To the side of one of the main pillars is screwed a steel arm or lever T to act as
a tension spring and a guide for chain which will be hereafter described.
To the underside of this main plate is also fixed a piece of steel to act as a
spring to the above last named guide to chain.
.
This main plate M is pierced for all necessary screws, pins studs and the arbor
of drum and also countersunk half its thickness to receive three of the before
mentioned wheels which will be flush with the underside of the main plate and
revolve free of the drum-From main pillar to main pillar before mentioned and
at bottom of same is screwed and pinned a plate of brass B about one sixteenth of
an inch in thickness and about half an inch in width pierced midway for the
reception of the arbor of the drum thus both plates form a top and bottom fixed
frame for drum. To this last named plate or bottom frame and on top side of
same is fixed a circular piece of thin steel R forming a spring and guide to chain
and partly encircling the drum to be further described hereafter.
On this bottom plate and encircling the hole for the reception of this arbor is a
small raised seat to prevent friction with the underside of the drum.
}
'
1
The bottom plate is screwed and pinned so that it can be taken off the pillars
when required. The top side of the main plate is encircled with a thin rim of
brass about one sixth of an inch in height fixed and forming one piece with the
same but somewhat less in circumference than the main plate and thus forming a
small projecting bead around same to hide the joint between it and the bottom
outside case. The rim on its top edge is cut away at two opposite sides of its
circumference about three quarters of an inch in length and slightly lessened in'
height to allow of two thin pieces of sheet brass passing to and fro over same for a'
purpose to be hereafter described.
To the above described rim is hinged the top part of the instrument containing
the glass Q, motion work, and the indicators to be described hereafter-This rim is
also pierced for the reception of a small steel spring catch to be hereafter described;

page_text: and which when fastened to above described rim secures the top containing the
glass, motion work and indicators to main frame.
On the top side of the main plate is fixed a thin inner rim N of brass about half
an inch in diameter concentric with the arbor of the drum thus forming on the top
of the main plate with the outer rim before described a kind of trough or receptacle
for the paper rings or dials to be hereafter described.
Fitting on the outside circumference of this inner rim is a closely fitting and
moveable thin ring of brass about one tenth of an inch in height having a small
flange on its top edge, at the bottom of this ring just about where it sits upon the
main plate and on its outside circumference is grooved a slight incision which is
deeper grooved at one place with special marks to indicate same on its bottom
edge, This groove or incision is for the purpose of temporary securing a thin sheet
of brass d no thicker than a sheet of note paper which has a circular hole made in
it equal to the area covered by the last mentioned ring and exactly the size of the
circumference of the incision and also a slight projection also marked to fit into
the incision on ring where marked deeper grooved than the rest so that if the sheet
of thin brass be laid on the ring with marks opposite to and corresponding to
marks on ring and both slightly pressed together the brass sheet will fasten itself
into the incision and also with a slight pressure unfasten when required
The paper dials G will be placed upon this thin sheet of brass which will be
of the form shewn on the drawings and have at its two opposite sides thin vertical
pieces fixed to it which are turned down to travel free and to pass over the top
edge of the outer rim where cut for them as before described-These vertical pieces
where turned down slightly project beyond the outer face of the outer rim for the
purpose of shifting the dials as required. The drum before mentioned is a correctly
guaged circle on plan and is made of solid brass and about one seventh of an inch
thick with slight projecting flanges top and bottom of it-Through the centre of its
circumference is fixed a steel circular arbor about one sixteenth of an inch in
diameter and slightly projecting from the bottom face of the drum to allow of it
fitting into the hole made for it in the bottom plate and free to revolve in same.
This arbor also projects from the top face of the drum and has fixed on it a toothed
wheel of twenty teeth which gears with wheels to be hereafter described-This
arbor passes through the circular hole pierced for its reception in the centre of the
top inain plate in which it is free to revolve and is also sufficiently long over same
to have fitted tightly upon it a circular piece of brass with a circular hole pierced
through its centre to receive this arbor,
This piece of brass is reduced in thickness about midway in its height which is
about one tenth of an inch and a thin steel spiral spring F is fitted on the rebate
BO formed and fixed to it at one end of same, the top end of this spring is made
wedge shaped for a purpose to be hereafter described-this piece of brass and the
spiral spring revolve with the arbor of the drum and has no friction with the top
plate The chain will be guaged steel rivetted and linked and similar to those used
on the fusees of watches and will be twelve inches and a half long or half an inch
longer than required to make four revolutions of the drum, it will be fastened at
one end to the side of the drum and the other end will be fastened to a piece of
steel to be hereafter described as the marker.
The top of the instrument will be made in the following manner-
A ring of brass is made to fit upon the top outer rim on the top main plate and
a slight circular rebate is formed in it so that the said rim may fit in and be flush
with it on the outside of the face of same and to project about one sixteenth of an
inch beyond the inside face of the said rim for the purpose of pressing upon the
dials and to keep the outside edges of same flat and steady. This ring for the top
of instrument is also rebatted to receive a thick clear glass top or face which fits
in same tightly and through which the dials may be seen, this is a convex glass
and circular on plan, this ring or frame for the glass is hinged securely to the outer
rim and on the outside face of same-In a slit formed in this ring or frame is
placed a thin steel spring fixed at one end and made to the same curve as the said

page_text: ring or frame and flush on the outside face of same so as to be invisible except at
one end to which is fixed a wedge shaped catch the ring last mentioned being
sufficiently cut away on its underside to allow of the free movements of same.
This spring catch when the top frame for glass is closed down on the outer rim fits
itself into a hole made for it in the said rim and the said catch being made to
project slightly at one end beyond the outside face of the rim is unfastened by a
slight pressure-By this means the frame and the glass top and also the motion
work and the indicators are fastened and unfastened to the rim of mainplate as
may be required. The last described ring or frame for the glass is slightly
reduced in thickness on its underside at two opposite places required for the free
movements of the vertical pieces fixed to the brass sheet under the dials before
described.
The glass top has a hole pierced or drilled through it perfectly central and
directly over the arbor of the drum and in this hole is fixed another and separate
arbor which being also circular and one sixteenth of an inch in diameter at this
place and having a screw thread formed on it passes through the glass top and is
fixed tightly upon the outside of same by a small cap of brass having a hole pierced
through it and with a screw thread formed in same to fit and screw upon the last
described arbor.
This arbor is fixed to a thin cap of brass about five sixths of an inch in diameter
and passes through the centre of same it being pierced for same.
This arbor on the underside of this cap is reduced to one third its diameter or
thickness and is sufficiently long to pass through the centre of a small pinion of
ten teeth and a small hollow tube or socket and which are free to revolve on Baid
arbor and to which socket the said pinion is fixed at top and to the other end or
bottom of this socket is fixed the fast indicator and immediately under this
indicator the socket is continued down and fixed to a circular piece of thin brass S
about one third of an inch in diameter on the underside of which from its centre
to its circumference are formed wedge like ridges and into any one of which may
fit the wedge shaped piece of steel formed on the spiral spring F attached to the
piece of brass on the arbor of drum, by this means when the drum is set in motion
the spiral spring revolving with the same and slightly pressing against the piece of
circular brass fixed to the fast indicator sets the latter also in motion.
Previous to fixing the fast indicator and piece of brass fixed to one end of same
it will be necessary to insert and pass the hollow socket which is fixed to the last
mentioned pinion through a hole made through the centre of a small wheel of
thirty two teeth-This last named wheel is supported by the bottom to cap C and
has a slightly raised nozzle on its underside which passes through a hole made for
it in a thin piece of brass and fixed to another socket to which is fixed the slow
indicator.
This last named piece of thin brass is somewhat less in diameter than the before
mentioned cap and forms a bottom to same-Two small wheels W fixed together
and superimposed with centre over centre and having a fixed pin or stud through
same which fits into a hole made for it in the cap before mentioned and is free to
revolve in same are enclosed in a space between the said cap and its bottom and
are free to revolve in said space. The top wheel has forty teeth formed on it and
gears with the pinion fixed to sockett of the fast indicator, and the bottom wheel
of thirty two teeth gears with another wheel of thirty two teeth fixed to the
socket of the slow indicator, by this means the fast indicator gives proportionate
motion to the slow indicator as required both revolving free of each other, The
cap C last described has a solid rim around it which on its underside has a slight
circular rebate formed in it to receive, and into which the bottom to cap is fixed
and by the above described means the indicators and motion work for same are
supported to the glass top and can be raised up and let down with same when
required to obtain access to the dials.
The underside of the main plate is countersunk in three places and half its
thickness for the reception of three wheels, One of these wheels is fixed to the arbor

page_text: of the drum as before described and gears with a wheel of forty teeth about half
an inch in diameter to the centre of which is fixed a pinion of ten teeth, the centrè
pin or stud of which fits into a hole made for it in the main plate and in which it
is free to revolve: A steel rack or bar with twenty five teeth formed on one side
of it crosses the wheel of forty teeth last mentioned and gears with the pinion of
ten teeth last named. This rack is placed close against a main pillar which is
partly undercut to allow it passing freely, opposite this pillar and also touching the
opposite side of the said rack is a piece of steel screwed tightly into the main plate,
Also fixed to the underside of the main plate is screwed and pinned a rectangular
piece of brass to act as another guide for the rack and touching same and made to
partly overhang same on underside and also the wheel of forty teeth last named
and is slightly undercut to allow of the free movements of said wheel and by this
means the said rack and wheel are supported and prevented falling out of position,
also tightly screwed and pinned to the underside of the main plate is another guide
for rack of narrow steel about three quarters of an inch long and placed close
against same, this guide also overhangs the last named wheel of forty teeth and
allows of the free movements of same and helps to support same in position and
thus the rack is guided in and out without material friction-To the outside end
of the rack is pinned a flat piece of thin brass on which pin it may turn so that
when the said rack is pushed under the main plate the flat piece may lie close
against the outside face of the bottom case of instrument.
By the above means it is intended that the chain if coiled around the drum and
pulled by the marker the drum and wheel fixed to its arbor will revolve and also
the last named wheel of forty teeth and the pinion fixed to same and therefore the
rack gearing with the last named pinion will be made to pass in and out of the
instrument sufficiently far that when the chain is uncoiled its full length and by
holding the instrument firmly fixed and pushing in the rack to its original position
under the main plate the pinion wheels and drum will be set in motion and cause
the chain to recoil around the drum. There is also another wheel of forty teeth
and pinion of six teeth fixed in centre of same the centre pin or stud of which fits
into a hole made for it in the under side of the main plate and is free to revolve
in same.
The said wheel and pinion last named are situated nearest to the opposite main
pillar to that mentioned nearest the rack.
On the under side and gearing with pinion of this last named wheel of forty
teeth which gears with the wheel fixed on the arbor of drum is another wheel of
forty teeth X which is screwed through its centre to the main plate and is free to
revolve on same and on the screw and thus both wheels and pinion are supported
and kept in position, upon the underside of the wheel which is screwed to the main
plate is fixed a circular raised seating which gradually thickens to one end of it and
thus forms a kind of circular wedge which will revolve with the said wheel when
in motion the purpose of which is to raise or lower a guide and tension spring T
for the chain as the last named coils around the drum. This guide and tension
spring consists of an arm of steel about an inch long pierced through at one end
and screwed through same to a main pillar and is free to partially revolve on same
screw. On the top side of this arm is fixed a short piece of vertical steel V which
just touches the circular wedge on wheel last named which as it revolves will raise
or lower the said arm according to the thickness of the wedge as required. In
order to assist the movements of the said arm a small thin piece of steel is made to
act as a spring by being fixed and screwed at one end of it to the main plate and
curved and rising up off same at the other end and constantly presses against the
short end of the guide the vertical piece of which is thus constantly kept slightly
pressing against the circular wedge before described-To the underside of this arm
or guide is fixed at one end of it a thin piece of steel the same length as the arm.
Pinned to the other end of the arm and placed over the end of this last named t
piece of thin steel is a small trough shaped piece of steel on which said pin it may
‘partially revolve so that it may always lie flat on the chain. The chain is made to

page_text: pass between this trough and the thin piece of steel which constantly presses upon
the flat side of the chain against the underside of the trough which last named lies
flat against same, as the arm is raised or lowered by this means the chain is always
kept in tension and truly guided around the drum.
As a further guide for the chain a thin piece of steel R is made to act as a spring
and is screwed tightly midway to the top side of the bottom plate or frame, it is
slightly curved on plan and is fixed almost tangent with two places on the side of
the drum and nearly touching same the two ends of this spring are slightly curved
and constantly press upon the flat side of the chain and are caused to rise up and
down with the movements of same, and the said pressure of springs upon the
chain causes the latter to coil closely around the drum The chain in its move-
ments is further assisted to coil truly by a thin piece of steel K about an inch long
and a quarter of an inch in depth which is fixed at one end into an incision made
for it in a small pillar fixed to the main plate, the flat side at the other end
constantly presses against the edges of the chain but gives way to the slightest
movement of same
The movement of the drum sets all wheels in motion.
The instrument will be enclosed on the bottom from the underside of the main
plate with a thin exterior casing of brass roughened on its bottom and which will
fit closely against and all round the underside of the said main plate and will be
screwed tightly to the main pillars on same. The said case will have a rectangular
hole pierced in it to allow of the chain passing through same and to allow of its
free movements, it will also be pierced to allow the end of the rack passing through
same and the free movements of same, there will be fixed to it a small ball of brass
to act as the catch and fastener for the marker and also a recess for point of same.
The said marker is a thin piece of curved steel about an inch long to which at a
place about one quarter of its length will be fixed the end of the chain, which is
previously passed through the hole in bottom case prepared for it. This marker
has immediately adjoining the end of the chain a thin pointer part of the same
piece of steel and at the other end of it a small piece the same depth as the pointer
and also part of the same piece of steel so that the said piece and the pointer will
touch the same plane and thus keep the pointer vertical to the said plane. This
marker will have a hole pierced through it to fit closely upon the ball of brass
fixed on the bottom case before mentioned, so that one end of the marker will cross
the hole made in case for the chain and thus keep out the dust, and also secure
the marker to the bottom case to the side of which it will lie against closely.
A ring of brass passed through a ball headed screw will be fixed by same to the
main plate just below the hinge and on the outside of case.
Upon the thin sheet of brass d which is placed upon the top of the main plate,
will be laid the dials or scales before mentioned, The dials will be circular rings
superimposed upon which will be marked and figured the several scales in separate
circles having a common centre as before described and made to fit into the trough
formed by the inner and outer rims on top of the main plate, These dials will
each have a hole cut out of the centre of them the area of which will be equal to
the outside circumference of the ring mentioned before as having an incision
formed on it so that these dials will fit around this ring which will be passed
through them with the flange on same partly overhanging the uppermost dial and
the thin piece of brass before mentioned as being placed under the dials will be
secured into the incision of said ring. The dials may be changed as often as
required as before described. The said dials and ring and said sheet of thin brass
can be partially revolved around the inner rim N both ways when the glass top is
secured down to frame as before described by means of the two vertical pieces of
thin brass fixed to the thin sheet of brass under the dials and which said vertical
pieces project beyond the outside face of the outer rim as before described. There
will be about twenty of these dials superimposed and upon each and every one will
be printed a separate scale in terms of chains, feet and links, or feet and inches as
the case may be and in the manner before described.

page_text: manner,
It will be necessary to prepare and set the instrument for use in the following
The glass top and with it the indicators, must be raised up and allowed
to fall back on its hinge and the dial or scale must be selected and placed upper-
most with zero or starting point opposite the hinge for top case, the said glasstop
with the points of the indicators slightly apart must then be closed down and
secured with the catch to frame. The marker must then be unfastened and pulled
so that both indicators will be exactly over each other, the dial or scale must
then be revolved by means of the vertical pieces so that zero or starting point
on same will be exactly under the points of the indicators, and to ascertain
the distance to said scale between any two given places on plan or drawing
the instrument must be moved and so placed that the point of the marker may
touch one of the given places the instrument must then be held firmly fixed with
the indicators still pointing to zero and the chain coiled around the drum and the
marker then pulled to the other given place on plan so that the point may touch
it and the indicators will then point to the required length by scale given on dial.
And if it be required to delineate a certain given length by scale the indicators
then must point to zero and the chain coiled around the drum and the pointer
pressed down to make a mark and the instrument held fixed and the marker then
pulled so that the indicators will point on the scale the given length and the
pointer should then again be pressed down to make a mark and the distance
between the two said marks will represent the given length according to the
scale used.
The instrument when made will be as near as possible the size shewn on the
drawings which represent same and each and every part of same where shewn
double full size little more or less.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed-I declare that what
I claim is
The invention of concentric scales figured and marked on separate circles of
different circumferences on separate rings or dials in terms of chains feet or links,
or feet and inches and such like in relative proportion each to the other and as
may be contained in each and every scale set out to the certain known size
or circumference of a circular drum and a guaged linked steel chain of a certain
length coiled around same and contriving by means of the motions of same causing
two indicators to revolve or traverse over said dials in due proportion to the size
of the drum and the length of the chain and contained in an improved instrument
for ascertaining by means of the same the lengths and distances or any division or
multiple thereof between separate places marked on plans sections and elevations
or such like drawn to said scales and also for delineating plans sections elevations
or such like to any given lengths to a given scale.