Improvements in Centro-lineads.
Year: 1890

page_text: Date of Application, 30th June, 1890-Accepted, 20th Sept., 1890
VODI DELE DIECIFICATION.
Improvements in Centro-lineads.
I, HENRY ADDISON HICKOK, of No. 17 West Park Street, Newark, New Jersey,
United States of America, Mechanical Engineer, do hereby declare the nature of
my invention for "IMPROVEMENTS IN CENTRO-LINEADS," and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
To avoid the annoyance caused by the want of a suitable device for drawing
perspective views and to provide a centro-linead or perspective linead by means of
which an accurate representation may be made of the details of the form and prin-
cipal lines of a body, for the purposes of mechanical or architectural constructions
is the principal object of this invention.
To this end, the invention consists in certain arrangements and combinations of
parts whereby a drawing instrument is secured for drawing lines which will, if
sufficiently prolonged, converge to a given centre, and whereby a centro-linead is
provided by means of which these lines may be accurately drawn.
In the drawings herewith accompanying, in which various forms of constructions
of the invention are illustrated,
Figure 1 represents a diagrammatic view of a perspective plan of an object and a
linear perspective of the same, the plane of the picture being represented upon the
drawing board, said view illustrating more especially the manner of the application
of my centro-linead in making perspective views when one or both of the vanishing
points fall outside of the drawing board or the drawing paper thereon.
Figure 2 is a plan view of the centro-linead and Figure 3 is a vertical section
through line in Figure 2.
Figure 4 represents a cross-section through line y, in Figure 2, and Figure 5 is
a similar view through line z in said Figure 2.
Figure 6 is an end view of a manipulating screw by means of which the instrument -
is adjusted.
Figure 7 represents a modified form of construction of the centro-linead in plan.
Figures 8 and 9 are sectional views of the same taken through line & in Figure 7,
illustrating the different positions of a pin or tack used in connection with the
instrument, and Figures 10 and 11 are similar views taken through line y in
Figure 7.
Figure 12 is a perspective view of the pin or tack employed with the instrument.
In the above described views, similar reference letters are employed to indicate
corresponding parts in each of said views.
In problems of descriptive geometry and in making perspective drawings, both
mechanical and architectural, the plane of the picture is usually taken between the
object to be represented and the point of sight in order that the drawing may be of
smaller dimensions than the object.
In the present case, in Figure 1, a drawing board is represented in outline and
apon the same the point of sight has been selected at C. A', B', represents the
borizontal trace of the plane of the picture and 1 on said line the perspective
point of the point 1 on the small plan of the object shown to the left on said sheet.
CC, is the vertical axis and upon the same the point 4 represents the point 4 shown
n the small elevation of the object also shown to the left on said sheet. A and B
re the vanishing points which are found mathematically and which in the present
case are shown, as A being off the drawing board and the other B being upon the
ame.
Having the point of sight given and having found the vanishing point, the
istances from said vanishing points to the vertical axis on the horizontal line

page_text: connecting said vanishing points, are then known and the instrument is adjusted
accordingly as will be described hereinafter, and can then be used in making the
drawing.
I will now proceed to the description of the construction of the centro-linead.
In the figures of the drawing, on sheet 2, d and d¹ represent two arms or straight-
edges which are pivotally attached to each other at their ends by means of a pin and
thumb-nut d so that the vertical plane passing along their inner edges of said
arms d and d intersect in the central axis of said pin.
Arranged upon the same pin and nut d² are two oppositely projecting arms or
plates d³ and d, preferably formed in one piece and one of which as d³ has secured
thereto by means of thumb-nuts d8 and d or in any other well-known manner, a
linead or rule d³, so adjusted that the vertical plane passing along the ruling edge
will also pass through the axis of the aforesaid pin d².
The other arm or plate d is provided with one or more graduated scales thereon.
To the arms or straight-edges d and at any convenient points thereon are
secured by means of screws or pins the plates e and e¹ having arranged thereon
upwardly extending posts or pins 2 and 3, the vertical axes of which lie in the same
vertical plane as the inner edges of the arms or straight edges d and d¹.
A slide is arranged upon the arm d' adapted to freely move thereon and which
receives a pin or post f¹ which in turn carries the nut or traveller f². the vertical
axis of the pin or post f1 being in the same vertical plane as that passing along the
ruling edge of the linead or rule d' and through the pin d².
Arranged upon the pins e², e³, and f¹ are the arms or links g and g¹ and upon
the plate or arm d are the lugs or bearings d and d, which are perforated and
carry a threaded rod or screw h, which rotates freely in said perforations. The
traveller is perforated and the perforation is provided with a thread which fits
the thread of a screw or threaded rod and thus causes the sliding movement of
the slide along the arm dt and over the scales thereon when the rod h is turned by
means of the thumb-nut or finger-piece . Collars 2 and 3 are secured to the
rod to hold the same in its bearings d and d' and also to take up any lost motion.
Thus when the rod is turned by means of its thumb-nut or finger-piece h³, the
traveller f² moves, carrying with it the slide to the proper place on the scale and
this movement is transmitted to the arms d and d by means of the links or arms g
and g' and varies the angle between the arms d and d¹ accordingly.
In applying the instrument to use, two pins i and i' are arranged in the drawing
board as will be hereinafter described.
When the arms d and d¹ have been properly adjusted by means of the adjusting
screw and the scale on the arm d, and the inner edges of the arms d and d¹ are
placed in contact with the pins i and, the point d2 of the instrument will move in
an are of a circle passing through the points and 1', and any line drawn along the
ruling edge of the linead d³, will, if prolonged, pass through the central point of the
supplementary are of which the distance between the pins and is the chord, which
point is perpendicularly removed from said chord, by a distance which corresponds
to the figure on the scale on the arm d to which the slide has been set.
Thus when the centro-linead is rotated, the inner edges of the arms d and d¹ being
kept in constant contact with the pins i and i¹, all lines drawn with the linead d³ and
prolonged will pass through the saine point as above described.
The operation of the device is as follows:-
Suppose, that by calculation, it has been found that the vanishing point A on the
line A B, Figure 1, at a distance of 60 inches from the line CC. The draughts-
man, according to circumstances may use any one of the scales on the arm d. If
he selects the scale to the right of the arm, Figure 2, and sets his slide to the
graduation mark 18 he must place the pins i and in a line perpendicular to the
line A B, said line being at such a distance from the line in Figure 1, that
said distance will be equal to 60 minus 18, or 42 inches from said point 4, the
distance between the said pins i and being 12 inches, equally divided on the
line A B; then all lines drawn with the linead d³, if prolonged, will pass through a

page_text: common centre which is the vanishing point A, and the length of a perpendicular
drawn from the line connecting the pins and to the centre or vanishing point
will, if measured in inches, correspond to the number on the scale to which the
instrument has been adjusted.
It will be seen from Figure 2 that three scales are shown on the arm d'; for the
scale to the right, as has been stated, the distance between the pins i and ¹ is
12 inches. If the middle scale. is used the pins i and ¹ are to be placed 18 inches
apart, and when the left hand scale is used said pins must be placed 24 inches
apart.
So far as the theory of the instrument is concerned it is evident that only one
scale and one position for the pins i and i¹are really necessary to correspond to any
position of the vanishing point. Practically however, if but one scale is used the
pins i and ¹ being near together and the vanishing point remote, the slide would
come too close to the pin d and thus interfere with the working of the main joint of
the instrument, and too, the divisions on the scale corresponding to the remote positions
of the vanishing point, would be too close together for convenience in setting. Also,
if but one scale and one position for the pins i and ¹ were used and the vanishing
point taken a short distance away, the length of the arm & would be so great as to
be inconvenient.
These objections have been met by using three positions for the pins i and i¹ to
which the graduations on the scales correspond, thus making the arm d convenient
in length and the divisions on the scales far enough apart to secure clearness and at
the same time sufficient variation in the vanishing point.
Of course it will be understood that the pins i and may, theoretically, be
placed any distance apart if the scales are graduated accordingly, but the scales
shown in the drawings are all that are necessary for the ordinary requirements of the
draughtsman.
!
From the above, it will be seen that the operation of the device is very simple and
it does not require great skill in manipulating.
It is my intention to supply in connection with the centro-linead a label upon
which the directions for use are printed and by means of which the draughtsman
can readily adjust the instrument and arrange the pins i and in the drawing
board.
Any strong round pin of very small diameter may be used in connection with the
centro-linead shown in Figure 2.
In Figure 7 is illustrated a modified form of construction of my centro-linead,
which is used in a like manner, against triangular pins j and j', as that described in
the above but in which I have dispensed with the use of the adjusting screw h and the
links and g¹.
In said construction the arms d and d¹ are provided with longitudinal slots d
and d¹¹ and instead of the links g and g₁ shown in the construction illustrated in
Figure 2, a bar g³ is used which slides upon the graduated arm or plate d* in guides,
as will be seen from said Figure 7. Said bar is provided with a series of con-
veniently spaced triangular holes 9' in which fit and may be forced therethrough the
triangular pins and j.
The operation of this form of centro-linead is as follows:-
When the vanishing point has been found and the scale and the graduation on the
arm d determined upon, as for instance the right hand scale, the reading edge of the
bar g³ is placed upon said graduation and scale, the pins j and j¹ are now inserted in
the perforations as shown in Figures 7, 8 and 10, which in this case (that is for the
right hand scale) are twelve inches apart, and the arms d and d¹ are brought against
the pins and screwed or clamped fast by means of thumb nuts d2 and d¹³ arranged in
the slots do and d¹ and the several parts of the centro-linead are thereby rigidly held
together, the reading edge of the bar g3 heing still in its original position. When the
said bar and the arms d and d¹ have been securely fastened to each other by said
thumb-nuts, the pins ; and j¹ are forced through the perforations in the bar 9³ and
firmly driven home in the drawing board J, being held in place therein by means of

page_text: '
the pins or points and so that the upper surface of the triangular pins is below
the lower surface of the bar gå, as is clearly, illustrated in Figures 9 and 11. The
inner edges of the arms.d and d are thus left free to rotate or move against the sharp
edge of the pin j and the instrument is then used in the same manner as has been
described.
I am. aware of the fact that numerous other means may be employed for adjusting
the arms d and d' without departing from the scope of my invention, but the
instruments shown in the present drawings are the preferred because they may be
easily manipulated and adjusted and at the same time the appearance thereof is more
sightly.
A further advantage of the said construction is that the parts are rigidly held in
position and still are free to move by means of the adjusting screw h shown in
Figure 2.
By this arrangement and construction, no matter how far the vanishing point is
taken from the vertical axis, (within the limits of the scale) however small the paper
and board upon which the perspective view is to be produced, this advantage is gained
that all lines drawn with my centro-linead will, if prolonged, intersect in the vanishing
point, whether said. vanishing point is accessible or not and a perspective view is the
result, all lines of which are correctly drawn.
Having now particularly described and ascertained the nature of my said inven-
tion; and in: what manner the same is to be performed, I. declare that what I
claim is
1. A centro-linead consisting of a linead or rule having straight-edges pivotally
attached thereto, so that the vertical planes passing along their inner edges intersect
in the central axis of their common pivotal pin, and arms or links co-operating with
said straight-edges, whereby the parts of the instrument are brought into their proper
and true relative. positions for use, so that the angle formed between said straight-
edges is definitely fixed in relation to the vanishing point, and means connected with
and joining, said arms, as set forth.
2. In a centro-linead, the combination with a linead or rule, of straight-edges
pivotally attached thereto, so that the vertical planes passing along their inner edges
intersect in the central axis of their common pivotal pin, and arms or links secured to
and co-operating with said straight-edges whereby the parts of the centro-linead are
automatically brought into their proper and true relative positions for use, and means
connected with and joining said arms, substantially as set forth.
3. In a centro-linead, the combination with a linead or rule, of straight-edges
pivotally attached thereto, so that the vertical planes passing along the ruling edge of
the linead and the inner edges of the straight-edges intersect in the central axis of
their common, pivotal pin, an arm or plate attached to said linead or rule, and arms or
links..connecting, said plate with the straight-edges for adjusting the same; for the
purposes set forth..
4. In a centro-linead, the combination with a linead or rule, of straight-edges
pivotally attached to said linead, so that the vertical planes passing, along the inner
edges intersect in the central axis of their common pivotal pin, an arint or plate
thereon provided with one or more graduated scales, a slide and means for connecting
said. slide to the straight-edges, for the purposes set forth.
5. In a centro-linead, the combination with a linead, of straight-edges. pivotally
attached: thereto, so that the vertical planes passing along their inner edges intersect
in the central axis of their common pivotal pin, an arm. or plate provided with
graduations thereon, a slide provided with oppositely projecting arms, and means: for
securing, and connecting the said arms to the pivoted straight-edges, for the purposes
set forth;
6. In a centro-linead, the combination with a linead, of straight-edges pivotally
attached thereto, so that the vertical planes. passing along their inner edges intersect
in the central axis of their common pivotal pin, an arm or plate provided with
graduations thereon a slide having oppositely projecting arms, means for securing the

page_text: said arms to the straight-edges, and an adjusting screw working in said slide and in
bearings on the graduated plate, for the purposes set forth.
7. A centro-linead, consisting of a linead or rule, straight-edges pivoted thereto,
and an arm or plate provided with one or more scales thereon for adjusting said
straight-edges, and links connecting said graduated plate with said straight-edges,
being secured to the latter by pins or post, the vertical axes of which lie in the same
vertical planes passing along the inner edges of said straight-edges, as and for the
purposes set forth.
8. In a centro-linead, the combination with a linead or rule, of straight-edges
pivotally attached thereto, so that the vertical planes passing along their inner edges
intersect in the central axis of their common pivotal pin, and arms or links for
adjusting said straight-edges, and means connected with and joining said arms, so that
all the parts of the centro-linead are brought simultaneously into their proper and
true relative positions and that the angle made by one of the straight-edges with the
rule will be exactly equal to the angle made by the other straight-edge with said rule,
as and for the purposes set forth.
9. In a centro-linead, the combination with a linead, of straight-edges pivotally
attached thereto, an arm or plate provided with graduations thereon, a slide having
oppositely projecting arms, means for securing said arms to the straight-edges, an
adjusting screw above said graduated plate working in bearings on said plate and a
traveller thereon, and a finger-piece for rotating said screw, as and for the purposes set
forth.
10. In a centro-linead, the combination, with a linead or rule, of straight-edges
pivotally attached to said linead, so that the vertical planes passing along the ruling
edge of the linead and the inner edges of the straight-edges intersect in the central
axis of their common pivotal pin, an arm or plate intermediately arranged between
said straight-edges, and an adjusting mechanism adapted to slide on said inter-
mediately arranged arm and connected with said straight-edges, for adjusting the
same, for the purposes set forth.
11. The combination with a pair of pins adapted to be driven into a drawing board,
of a centro-linead consisting of a linead or rule having pivotally attached thereon two
straight-edges in such a manner that the vertical planes passing along the ruling edge
of the linead and along the inner edges of the straight-edges intersect in the central
axis of their common pivotal pin, and arms or links co-operating with said straight-
edges and means for connecting and joining said arms whereby the same are brought
into their true relative positions for use, so that the angle formed between said
straight-edges is definitely fixed in relation to its vanishing point, substantially as and
for the purposes set forth.
12. A centro-linead combining therein a linead or rule, straight-edges pivotally
attached to said rule in such a manner that the vertical planes passing along their
inner edges intersect in the central axis of their common pivotal pin, and a plate or
arm provided with one or more scales, and means adapted to be set to any one of the
graduations on said scales or scale and connected with the straight-edges for adjusting
the same, for the purposes set forth.
1
CT
1000
HENRY ADDISON HICKOK.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicant.