IMPROVEMENTS IN BRICKS OR BLOCKS FOR BUILDING PURPOSES
Year: 1882

page_text: LETTERS PATENT to John Henry Johnson of 47 Lincolns Inn Fields in
the County of Middlesex Gentleman for an Invention of "IMPROVEMENTS
IN BRICKS OR BLOCKS FOR BUILDING PURPOSES "-Communicated to him
from Jean Darrigan a person resident at Vagnotte (Landes) in the Republic
of France
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 2nd December 1882.
"
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex,
Gentleman, "IMPROVEMENTS IN BRICKS OR BLOCKS FOR BUILDING PURPOSES
a communication to me from Jean Darrigan a person resident at Vagnotte (Landes)
in the Republic of France,
This Invention relates to bricks or blocks for building purposes generally but
the improved bricks or blocks made with double interlocking or compound
dovetails in accordance with the said Invention are more especially adapted for
the construction of the horizontal parts of buildings such as floors vaults stairs
paving and the like. These structures when composed of the improved bricks or
blocks hereinafter described are self sustaining, that is to say, require no horizontal
beams or bearers of wood iron or other materials to support them. The improved
bricks or blocks are provided on two sides with a recess of trapezoidal form in
transverse section, that is to say, in the form of a dovetail or its equivalent. These
recesses are of a taper form longitudinally and are so arranged as to taper in
reverse directions relatively to one another on opposite sides of the brick or block
and their mean width is equal to one half of the width of the brick or block.
This arrangement enables the dovetail tenon formed by two of the projecting
parts of two adjacent bricks or blocks to fit exactly into the recess of the corre-
sponding brick or block in the next row as hereinafter described and thus bind all
the parts of the whole structure together in a longitudinal as well as in a transverse
direction, By the aforesaid reverse tapering of the recesses on opposite sides of
the same brick or block it becomes impossible by applying force in any direction
to separate any one brick or block from the rest of the structure without breaking
the parts which are firmly interlocked or bound together independently of the
adhesion of the cement or mortar which may be used,
By the employment of the Improved bricks or blocks, great strength is imparted
to the structures, in which they are employed, and not only is all lateral thrust
apon the supporting walls entirely avoided but the latter are on the contrary
strongly connected or bound together in a horizontal direction.
In all cases as the bricks or blocks constructed according to this Invention are

page_text: intended to be laid in an inclined position similar to that of the stones of an arch
their lateral surfaces are in the form of a parallelogram whose angle determines the
inclination at which the bricks or blocks are to be set. The consequence of this
arrangement is to partially convert the pressure exerted perpendicularly to the
surface of the floor or other structure into a lateral pressure. The bricks or blocks
may however be of rectangular form and be arranged perpendicularly to the
surface of the structure.
The form and dimensions or proportions of the improved bricks or blocks may
vary considerably provided that the dovetail recesses whose taper or direction of
contraction with respect to one another is inversely arranged at opposite ends of
the brick or block are capable of such proportions as to be capable of receiving
or containing the two projecting parts or dovetail tenons, of two bricks or blocks in
the next row, the width of the recess at this underside of the brick, being equal
to the width of the two dovetail tenons or projecting parts at the upper side and
vice versa.
The operation of laying the improved bricks or blocks is performed in the
following manner;
- Assuming that it is required to form four vertical walls, for example, by a
horizontal floor or structure, the improved bricks are laid in a row upon one wall,
so that the widest part of the recesses which are to receive the projections on the
succeeding row shall be upwards and when inclined or lozenge shaped bricks
are employed, the bricks should incline outwards or away from the space that is to
be covered.
The first row of bricks thus laid now presents on the inner side.at each joint a
tongue or projection in the form of a trapezoid or dovetail, divided in two parts
belonging to two adjacent bricks. The narrowest part of these tongues or
projections is at the top and after applying a suitable mortar or cement, the bricks
of the next row are then placed in position by causing the dovetail recesses with
which they are provided to slide over the corresponding dovetail tongues presented
by the first row. The succeeding rows are laid in the same manner and the
component parts of the whole structure are thus securely interlocked by reason of
the compound character of the dovetail joints.
Stairs built with the improved bricks should be erected simultaneously with
the vertical walls, it being necessary for one extremity of each step to be engaged
in the wall.
The improved bricks or blocks may be made of baked or burnt clay, cement,
hardened plaster or any materials capable of being employed in the manufacture of
artificial Stone or bricks.
In cases in which it is desired to obtain a structure possessing great lightness,
combined with strength, the improved bricks or blocks may be made hollow,
The internal surfaces of the recesses may be made parallel if necessary and holes
may be formed in the bricks for the reception of pins or dowels in cases where
extra strength is needed.
The improved bricks or blocks are preferably formed by means of moulds
specially constructed for the purpose and which may consist of two correspondingly
formed valves which meet along the middle of the smaller sides of the brick, the
recesses are formed by means of wedge shaped blocks of corresponding formed which
project from the sides of the mould and one of which works in slides so as to be
capable of being drawn and after moulding the brick or block for the purpose of
enabling the latter to be taken out of the mould at the opposite extremity.
Pressure may be applied in the mould either in a direction perpendicular to the
sides of the brick or block or in the direction of the length of the latter. In the
latter case the blocks for forming the recesses may be permanently attached to
the mould the two halves of which may then be removed by sliding them off in
opposite directions.
+

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
2nd June 1883.
.
"
"
JOHN HENRY JOHNSON of 47 Lincolns Inn Fields in the County of Middlesex,
Gentleman IMPROVEMENTS IN BRICKS OR BLOCKS FOR BUILDING PURPOSES
a communication to me from Jean Darrigan, a person resident at Cagnotte [sic]
(Landes) in the Republic of France.
This Invention relates to bricks or blocks for building purposes generally but the
improved bricks or blocks made with double interlocking or compound dovetails in
accordance with the said Invention are more especially adapted for the construc-
tion of the horizontal parts of buildings such as floors, vaults, stairs paving and the
like. These structures when composed of the improved bricks or blocks herein-
after described are self sustaining that is to say require no horizontal beams or
bearers of wood iron or other materials to support them-The improved bricks or
blocks are provided on two sides with a recess of trapezoidal form in transverse
section that is to say in the form of a dovetail or its equivalent-These recesses
are of a taper form longitudinally and are so arranged as to taper in reverse
directions relatively to one another on opposite sides of the brick or block and
their nean width is equal to one half of the width of the brick or block. This
arrangement enables the dovetail tenon formed by two of the projecting parts of
two adjacent bricks or blocks to fit exactly into the recess of the corresponding
brick or block in the next row as hereinafter described and thus bind all the parts
of the whole structure together in a longitudinal as well as in a transverse direction.
By the aforesaid reverse tapering of the recesses on opposite sides of the same brick
or block it becomes impossible by applying force in any direction to separate any
one brick or block from the rest of the structure without breaking the parts which
are firmly interlocked or bound together independently of the adhesion of the
cement or mortar which may be used.
The improved bricks or blocks although capable of being laid flat in the same
manner as common bricks when employed in the construction of walls or partitions,
are more especially intended to be laid vertically on edge or preferably in an inclined
position and to be thus employed in the construction of floors vaults galleries and
other like structures.
By the employment of the improved bricks or blocks great strength is imparted
to the structures in which they are employed and not only is all lateral thrust
upon the supporting walls entirely avoided but the latter are on the contrary
strongly connected or hound together in a horizontal direction Instead of making
the dovetail surfaces of rectilinear form curved or angular surfaces may be employed
with one or more steps or angles, provided that the taper or equivalent contraction
of the recess is reversed on opposite sides of the brick or block so to produce the
required effect.
In all cases as the bricks or blocks constructed according to this Invention are
intended to be laid in an inclined position similar to that of the stones of an arch
their lateral surfaces are in the form of a parallelogram whose angle determines
the inclination at which the bricks or blocks are to be set. The consequence of
this arrangement is to partially convert the pressure exerted perpendicularly to the
surface of the floor or other structure into a lateral pressure. The bricks or blocks
may however be of rectangular form and be arranged perpendicularly to the surface
of the structure.
And in Order that the said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to

page_text: .
the accompanying sheet of drawings in which various forms or arrangements of the
improved bricks cr blocks and the mode of connecting them together are fully
illustrated.
Figure 1 is a front elevation side elevation and transverse section of a brick
constructed according to this Invention.
Figure 2 is a general view in elevation and plan shewing the method of joining
the said bricks.
Figure 3 is an elevation of one of the improved bricks perforated for the reception
of pins or dowels as hereinafter explained.
Figures 4, 5, 6 and 7. represent in elevation different forms of bricks made in
accordance with this Invention.
Figures 8, 9, 10 and 11 are horizontal sections also illustrating different forms of
the improved bricks.
Figure 12 is a complete developement of the several surfaces of an improved brick
showing the arrangement of the compound dovetails.
Figures 13 to 17 are side elevations of different forms of bricks.
Figures 18 and 19 represent on a smaller scale horizontal structures composed of
the improved bricks.
Figure 20 illustrates the application of lateral dovetailed grooves to bricks
constructed according to this Invention.
As shown in the drawing the form and dimensions or proportions of the improved
bricks or blocks may vary considerably provided that the dovetail recesses whose
taper or direction of contraction with respect to one another is inversely arranged
at opposite ends of the brick or block are of such proportions as to be capable of
receiving or containing the two projecting parts or dovetail tenons of two bricks or
blocks in the next row as shewn in figure 1, the width of the recess at E F being
equal to the width of the dovetail tenons or projecting parts at C. D and c¹ d'
combined and the width of the recess at e¹ f1 equal to the total of the width of the
tenons or projecting parts at A B and a¹ b¹. The sides of the recess from the
point B to the point D and from the point b¹to the point d' may be straight curved
or crooked as shewn by way of example in figures 1 to 6.
The drawing shows clearly the arrangement of all the parts as well as the
compound dovetail form of the joints. As shewn in figure 2 the projections and
recesses are arranged alternately being so proportioned and combined that when a
series of bricks B. B'. B are laid together in a row the projecting parts of the
adjacent bricks form at the junction of the said bricks a series of perfect dovetail
tongues or tenons Q Q on one side of the row and a similar series q¹ q on the
other side of the same row. In addition to the ordinary dovetail taper the tongues
or tenons on one side of the row taper from the upper side of the structure to the
under side of the same and taper in the opposite direction on the other side of the
saine row thus forming the compound dovetail herein before referred to. The
tenons qq on the front side of the row of bricks B. B'. B². fit exactly into the
corresponding recesses in the next row of bricks one of which is shown in the
drawing at C and so on throughout the whole of the structure.
The sectional form of the recesses may be varied in many ways Three different
forms are illustrated by way of example in figures 8, 9 and 11. Figure 10 shows
a section of a brick with straight recesses. This form of brick may be employed in
structures which are adequately supported in two opposite directions or for
covering a surface or structure that is already bound together in all directions
For ordinary purposes the improved bricks or blocks are inclined or lozenge
shaped as shewn in figures 13, 14, and 15, the sides being inclined at any suitable
angle. In bricks or blocks of a given size the bearing surface increases and the
thickness diminishes in proportion to the angle at which the sides are inclined as
shewn in the said figures 13. 14 and 15 This inclination causes the bricks or
blocks to bind more strongly together and facilitates their manipulation but may
be dispensed with in the case of vertical walls and small or narrow surfaces such
as steps The inclination is also dispensed with in building arched structures as

page_text: arch.
in this case the bricks are of a taper form corresponding with the pitch of tho
This modification only affects the flat sides of the bricks or blocks, the form
of the recesses and projections remaining unaltered. These bricks may be employed
for the first course of bridges of limited length.
The operation of laying the improved bricks or blocks is performed in the
following manner :—
Assuming that it is required to join four vertical walls for example by a
horizontal floor or structure, the tops of the walls are first carefully levelled and
the improved bricks are laid in a row upon one wall so that the widest part of the
recesses which are to receive the projections on the succeeding row shall be
upwards and when inclined or lozenge shaped bricks are employed the bricks
should incline outwards or away from the space that is to be covered. A certain
amount of play between the recesses and projections is allowed for in moulding
the bricks, this play being equal between the surfaces of all the joints serves to
contain the mortar cement plaster or other binding agent which may be employed
to give solidity to the structure. The angular space outside the first row of bricks
is to be filled up with bricks of the same form cut or divided diagonally or with
common brickwork. This first row of bricks thus laid now presents on the inner
side at each joint a tongue or projection in the form of a trapezoid or dovetail
(Figure 2) divided in two parts belonging to two adjacent bricks. The narrowest
part of these tongues or projections is at the top and after applying a suitable
mortar or cement the bricks of the next row are then placed in position by causing
the dovetail recesses with which they are provided to slide over the corresponding
dovetail tongues presented by the first row The succeeding rows are laid in the
same manner and the component parts of the whole structure are thus securely
interlocked by reason of the compound character of the dovetail joints.
The ends of the rows are made even if necessary by means of half bricks
(figure 7).
In order to construct external galleries the structure composed as hereinbefore
described of the improved bricks must be extended beyond the vertical walls to a
distance corresponding to the width of the gallery. In this case it is necessary
either to employ the perforated bricks illustrated in figure 3 or to perforate and
pin the bricks after they are laid. Supports may also be provided by means of
consoles constructed with the improved bricks It is unnecessary to provide
supports for the bricks during the course of construction as the bricks already in.
position support those of the series which is in the course of being laid and the
lateral walls prevent the fabric from falling bodily. Stairs built with the improved
bricks should be erected simultaneously with the vertical walls it being necessary
for one extremity of each step to be engaged in the wall.
When the length of any structure such as a bridge composed of the improved
bricks or blocks necessitates an arch or curve, bricks or blocks with unequal ends
(figure 17) are employed for the first course, cominencing to build upon the two
abutments at the same time and joining the fabric at the middle with a brick or
block having the largest part of the two recesses turned downwards or simply by
keying the structure with plain bricks or stones. The bridge in course of con-
struction may be supported on trestles or props placed at a suitable distance apart.
A horizontal structure constructed according to this invention by the employment
of the improved bricks or blocks hereinbefore described is illustrated in figure 18.
Figure 19 represents a similar horizontal structure of undulating form constructed
with tapering blocks k whereby greater strength is obtained than in the case of
the flat structure. In order to obtain a flat surface the hollows on the upper side
of this undulating structure may be filled up with hollow bricks or tiles ¹ the
hollows on the underside being concealed by a wire fabric sustaining a plaster or
other surface.
The brick or block illustrated in figure 20 is constructed with dovetailed grooves h
on the two lateral surfaces for the purpose of imparting additional strength to the
structure by causing the cement to fill these grooves and thus bind the parts more

page_text: firmly together. These grooves are made at right angles to the large sides of the
brick to facilitate the removal from the mould.
The improved bricks or blocks may be made of baked or burnt clay cement,
hardened plaster or any materials capable of being employed in the manufacture of
artificial stone or bricks and may present smooth or roughened surfaces as desired.
In cases in which it is desired to obtain a structure possessing great lightness.
combined with strength the improved bricks or blocks may be made hollow. The
internal surfaces of the recesses may be made parallel if necessary in order to
enable them to be moulded by passing through a moulding orifice. The weight of
the bricks or blocks may be lessened by the employment of suitable materials such
for example as a mixture of brick earth with sawdust straw refuse fibres and other
like substances which being destroyed in the burning process render the brick
porous and light.
The improved bricks or blocks are preferably formed by means of moulds
which are specially constructed for the purpose and which may consist of two
correspondingly formed halves which meet along the middle of the smaller
sides of the brick the recesses are formed by means of wedge shaped blocks of
corresponding form which project from the sides of the mould and one of which
works in slides so as to be capable of being drawn out after moulding the brick
or block for the purpose of enabling the latter to be taken out of the mould at the
opposite extremity. Pressure may be applied in the mould either in a direction
perpendicular to the sides of the brick or block or in the direction of the length of
the latter. In the latter case the blocks for forming the recesses may be perma-
nently attached to the mould the two halves of which may then be removed by
sliding them off in opposite directions.
Horizontal structures constructed as herein before described according to this
invention may be supported if necessary by iron beams or girders placed at
suitable intervals and thus enabling the thickness of the structure. to bei
diminished.
'
The expansion of these supports will not affect the sills or blocks employed in
the structures which they sustain.
Having now described and particularly ascertained the nature of the said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is :-
First.-The improved bricks or blocks for building purposes with double inter-
locking or compound dovetails by means of which it is rendered possible to construct
horizontal partitions of all descriptions such as floors flat or arched vaults galleries
stairs and the like without the employment of auxiliary horizontal supports and
without exerting any lateral thrust upon the vertical supporting walls substantially
as herein before described and illustrated in the accompanying drawings..
Second. In bricks or blocks for building purposes providing recesses of trape-
zoidal or dovetail form in the opposite sides of such bricks or blocks the dimensions
of the said recesses being equal to the remaining or projecting part on each side
thereof substantially as hereinbefore described and illustrated in the accompanying.
drawings.
Third. In bricks or blocks for building purposes made with interlocking pro-
jections and recesses as hereinbefore set forth tapering the said projections in
reverse directions on opposite sides of the bricks substantially as hereinbefore
described and illustrated in the drawings
.
Fourth. In bricks or blocks for building purposes made with interlocking
projections and recesses as herein before set forth making the ends of the said bricks
in the form of a double T the said ends being bevelled or inclined so as to present
an even surface when the bricks are laid in an inclined position after the manner
of the stones of an arch substantially as herein before described and illustrated in
the drawings.
-
.

page_text: Fifth. In bricks or blocks for building purposes the provision of means for
connecting the said bricks or blocks together consisting in causing the projecting
parts of two adjacent bricks or blocks in one row to fit into and engage with the
combined recesses in the corresponding bricks in the two adjacent rows on both
sides of the first mentioned row substantially as hereinbefore described and
illustrated in the drawings.
In witness whereof I the said John Henry Johnson have to this my Specifi-
cation set my hand and seal this first day of June One thousand eight
hundred and eighty three.
J. HENRY JOHNSON (LS)