IMPROVEMENTS IN ASTRAGALS AND SASH BARS FOR CARRYING GLASS. AND IN GLAZING
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by James Harley at the Office of the
Commissioners of Patents on the 7th November 1881.
JAMES HARLEY, of Glasgow, in the County of Lanark, North Britain, Civil
Engineer. "IMPROVEMENTS IN ASTRAGALS AND SASH BARS FOR CARRYING GLASS.
AND IN GLAZING."
This Invention has for its nature and object, (1) the production of an improved
form of astragal or sash bar for carrying glass, particularly in roof lights, roof
windows, sheds, railway stations, conservatories, and other buildings and structures,
where, instead of being vertical or perpendicular, the glass lies in a horizontal or
sloping position; and, (2) arrangements whereby astragals with soft ductile metal
glazing may be made to carry any number of overlapped sheets of glass in a vertical
or sloping position.
My improved sash bar is a combination of (first) a core constructed as herein-
after described, and (second) of a system of sheet lead glazing attached to the
said core, and more or less completely clothing or enveloping and protecting the
same, lining the gutters thereof, forming a soft couch or cushion for the glass, and
serving as a substitute for putty or other plastic fixing in glazing the upper or
outer surface of the glass as hereinafter described; and that (thirdly) either with
or without a cap fitting down over the top of the central feather of the astragal or
inserted into the core thereof in such a way as that the said cap shall press down
upon the lead glazing and retain the same firmly in its place, as hereinafter
described.
An astragal intended to support the edges of two adjacent sheets of glass lying
one on one edge and the other on the other edge thereof, must have a centre feather
or midrib to prevent the sheets of glass from coming in contact or slipping sidewise,
and also wings on each side of the midrib on which the sheets of glass may rest,
or on or against which they may be supported and in situations where the glass
lies in a horizontal or sloping position it is, if not necessary, at least highly
advisable, that the astragal should have gutters or channels underneath the glass
to carry off rain or moisture penetrating past the edges of the glass, and which if
not carried off by such gutters would drop into the apartment below.
From an ancient date sheet lead has been used in one form or another to fasten
or retain the sheets of glass in their position in or upon the astragal, and the sheet
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page_text: lead used for that purpose has also in many cases of recent years been made to
subserve the additional purposes of wholly or partially protecting the metallic core
or backbone of the astragal against weather action, and the action of water and
corrosive vapours, and of forming a soft or dull couch or cushion for the glass, to
break or diminish the violence of concussions and vibrations which might tend to
fracture it. Astragals which carry glass in a horizontal or sloping position may be
so used as to carry the whole weight of the glass or only part of it.
Where a pane
or sheet of glass in a roof rests with its upper and lower edges (that is, the edges
parallel to the ridge or eaves) on suppors, the astragals on which the side edges
rest carry only part of the weight, namely, that part not carried by the supports of
the top and bottom edges of the sheet, and for such a purpose astragals of weaker
construction, such as the common astragals of folded sheet zinc and similar sheet
metals capable of being drawn cold through dies into various sectional forms may
be used. But astragals may also be required to carry glass across a space in a
roof longer from top to bottom than can be covered by one sheet of glass, and in
that case the astragals must bear the entire weight of a series of sheets overlapping
or overlapped at their top or bottom edges, and not supported there by any
transverse supports commonly called purlins. In these cases stronger astragals are
required, and hitherto such astragals have been made of a core of solid iron or
other solid metal, with or without a system of lead glazing attached thereto.
Such astragals with a core of solid iron have the merit of very great strength, but
it is an objection that their weights detracts from their useful strength, since that
-weight itself-contributes to increase their liability to yield to deflecting or transverse
strains, and to assume a permanent set under the same; and where there are many
such astragals used in a roof, their aggregate weight on the roof is an
inconvenience.
The general principle on which I propose to construct such astragals is to
substitute for such solid core hollow or tubular cores of the same or any other
similar or convenient section, thus obtaining with the same or with even a greater
amount of strength and rigidity, and capability of span, or at all events with an
amount thereof adequate for all or most practical purposes, and also with a greater
resistance to deflecting strains and power of recovery therefrom, the important
advantage of greater lightness in the astragal and in the general structure of the
roof. By hollow or tubular I mean not only cores of a continuous and unbroken
hollow or tubular section, but also those in the section of which segments of circles
and other curves or corrugations are employed to give rigidity to the thin slicet
metal of which the core is formed. The sectional outline of such hollow or tubular
cores may be very various in the details, the range of variation being limited only
by the necessity of providing a central feather and side wings, preferably
guttered, of disposing the material of the bar so as to obtain an adequate amount
of strength and resistance to the compressive strains, which the upper and
the tensile strains, which the lower parts of the bar require to sustain (and which
object is to be effected by removing said material as far as possible, or as necessary,
from the neutral axis of the bar), of having the wings supported with sufficient
power to resist any danger of their breaking or bending under the weight of the
glass and its occasional superincumbent loads, as of snow and the like, and with
sufficient steadiness to avoid vibration; and lastly, of being capable of being rolled
or otherwise modelled with sufficient ease and cheapness, and of being conveniently
enveloped in a clothing of lead as aforesaid. 1 hereinafter describe a number of
sections which I regard as combining these objects or conditions of suitability in a
satisfactory way, but they are all liable to an indefinite amount of variation
without affecting the substantial identity of principle in the construction of them.
My core may be formed in either of two ways, that is to say, the outline of it
may consist of one continuous and unbroken outline of sheet iron or sheet steel, or
thin ion or thin steel, or of thin copper or other inetallic alloy in which ductility
and rigidity of strength are combined, such as may be produced by taking a tube

page_text: of such iron, steel, or other such metal, and compressing the same (by passing it
while heated to the requisite temperature through a rolling mill, or by applying to
it other well known mechanical contrivances) into the sectional outline required;
or I may take a strip of such sheet iron, copper, steel, or metallic alloy, and may
bend or compress the same while heated as aforesaid by longitudinal folding into
a bar or core of such cross section as I require without welding or uniting together
the edges of the strip. And in some cases the bar so formed from a strip of sheet
iron, steel, copper, or metallic alloy, may be strengthened by additional separate
pieces connected with it as hereinafter mentioned.
The cores constructed from strips of sheet iron, steel, copper, or metallic alloy
may be made in their simplest form by merely folding a flat strip of such sheet
inetal into the forni of an arch or half tube, with a wing projecting on each side,
the wing being either simply curved into a semicircular gutter, or bent so as to
present in section one or two or more alternate concavities and convexities, or a
series of corrugations; or the walls of the arch may be brought closer together or
into contact. And in the last case a hollow bead or tube may be left at the top of
the walls, and running along the ridge of the compressed arch or central feather,
in which hollow bead a rod or tube of iron or steel may be fixed, with an iron or
steel strut or struts projecting downwards to the level or below the level of the
wings, and with an eye or other contrivance in the lower end of the strut or struts
for passing ties of stout wire through, or attaching the same to the end of the strut
or struts and to the ends of the said rod or tube, the strut or struts and the ties
being wholly or partially within the walls of the central feather, and the ties being
wholly or partially within the walls of the central feather, and the sheet metal of
the walls being pressed together round the streets.
Or a steel or iron bar of a section like an anchor shank may be so inserted as
to be held fast by the bead, or roll, or flange at the top of the anchor shank, may be
so inserted as to be held fast by the bead, roll, or flange thereof in the said tube
left along the ridge of the central feather, the part corresponding to the anchor
shank passing down between and projecting beyond the walls of the compressed
arch, and the portions corresponding to the flukes of the anchor being brought up
under the outer edges of the wings and gripped fast there by a downward fold of
the sheet metal at the edges of the wings over the points of the flukes. A stouter
form of core may be made by compressing a tube of thin iron, steel, copper, or
suitable metallic alloy, longitudinally along the upper quadrants of its circular
section, so as to form a central feather and a guttered wing on each side thereof,
and the rest of the tube may either be allowed to retain its original curves, or the
part of the sectional outline from the edge or top of the wings downwards may be
obviously modified, as by being compressed into a deeper or more pointed form,
like that of a heart, or the lower part may be compressed still further and drawn
out into the form of a keel, running longitudinally along the lowest part of the
tube.
Or the tube may be compressed into a central feather above, and the rest of it
into an outline, somewhat resembling a trefoil, by forming a longitudinal indenta-
tion or depression for a gutter on each side of the central feather, and two like
indentations on opposite sides of the tube below the wings. It is obvious that
the different outlines into which the sections of the tube may be compressed are
very numerous, the central feather may be long or short, and either hollow or with
its walls in contact, the gutters may be deep or shallow, curved, rectangular, or
pointed; the lips or shoulders of the gutters inay rise to near the level of the top
of the central feather, or the pressure on the tube may be applied so as to depress
the wings, and the hollow tubular portion beneath them, down below the horizontal
diameter of the tube, so that the outline of my hollow core shall be the same as, or
shall closely resemble that of the ordinary solid metallic cores in use at the present
day, and shall be practically what such solid metallic core would be if the interior
mass of its metal had been removed and nothing left but the external skin of metal

page_text: all round the margin of its sectional outline. Again cores of similar section to
those obtained by the compression of a tube may be produced by folding or com-
pressing a sheet of iron, steel, copper, or suitable metallic alloy into such sectional
forms as may be desired, and the flat sheet may have its edges folded either
upward or downwards, so as to have the point in the section where the two
unjoined edges of sheet metal meet, either at the top or the bottom of the core.
In cases where the hollow or tubular bottom of the core may not be considered
sufficiently strong to cross spans of unusual width, especially in hollow sections
whose outline resembles those of the solid metallic cores at present in use, the core
may have its strength and elasticity largely increased by introducing sheathwise
into the hollow bottom a strip of corrugated sheet iron or steel of such a section
that its edges will strongly bear at the inner surfaces of the outer extremities of
the wings, and that the points of its corrugations will bear in like manner
alternately against the upper and lower internal surfaces of the hollow. In the
case of the use of the girder shaped cup, hereinafter described, the corrugated strip
should be so shaped and adjusted in the hollow that its centre corrugation may
press up against the lower flange of the girder bar, and its extending corrugations
to right and left may clear the edges of said flange and bear directly on the inner
surfaces of the hollow core.
To the cores forined in any of the ways mentioned I attach a system or
arrangement of thin sheet lead in which I envelope or clothe the whole or part of
the whole outline of the core.
I either envelope the whole outline of the core with a complete continuous and
unbroken covering of sheet lead having a double fold of the lead projecting from
each side of the central feather at or just above the level at which the upper
surface of the glass when placed in position on the wings would be, so that such
double folds shall be capable of being pressed down over the edges of the upper
surface of the glass as a substitute for putty.
Or I envelope the whole of the bottom or underpart of the core, including the
wings, in sheet lead, bringing the lead up over the lips of the wings on which the
glass rests, down each gutter, and up each side of the central feather to such a
height as will permit of the longitudinal edges of the strip of lead being, after the
glass is placed in its position, folded down over the edges of the glass for the
purposes aforesaid. The object of so applying an entire or partial clothing of lead
to the core is to protect the parts of iron or steel exposed to weather, moisture,
and vapours, and the like corroding influences therefrom, particularly to protect the
bottom parts, which are turned to the interior of the building, from such corrosive
fumes, in sheds where chemical and similar manufactures are carried on, or in
railway stations where there is a discharge of sulphuretted vapours; also to line
the gutters so as to obviate the effect of the corroding action of water on the iron
or steel; to form on the lips of the gutters or wings whereon the glass rests a soft
or dull couch, which will help to mitigate the effect of concussions or vibrations
which would otherwise make the glass rattle against the hard metal of which the
core is composed, and finally to afford a substitute for putty or other plastic fixing
in the glazing of the glass.
When I envelope the whole core in lead I effect this purpose very readily by
slipping the core into a tube of sheet lead of the requisite diameter, and then
beating or rolling or otherwise pressing the lead closely and firmly to the outline
of the core (or to those parts of it to which it is necessary or advisable to make the
lead adhere and fit closely), drawing out and flattening down the surplus lead
(beyond what is required to form the general covering or envelope of the core) into
the above mentioned double-ply wings or projections which are to serve as substi-
tutes for putty. Where I use a strip of sheet lead for completely enveloping the
I can solder the edges at their line of junction.
core,
I also in some cases adjust to the top of the central feather of the core, after it
has been wholly or partly swathed in lead, a cap intended principally to press

page_text: down with its side wings or flanges on the edges of lead, which form a substi-
tute for putty, in order to retain the lead in its place to prevent it from rising off
the surface of the glass through any accidental causes. This cap may be variously
constructed and applied. Where in a core formed from sheet metal the central
feather is formed of the two outer and unjoined edges or margins of a strip of
sheet metal, the margins or walls not being in contact, and where also at the same
time the top or upper surface of the central feather is on a level with the upper
surface of the glass, the cap may consist of a girder-shaped bar of iron, with a
flange above of sufficient breadth to cover the lead glazing on each side, and with
a flange below of sufficient breadth to catch the inner or under surface of the
gutters in the wings to right and left, so that the cap cannot by reason of this
flange catching the wings be lifted upwards out of the core, and the perpendicular
bar or rib of the girder connecting its upper and under flauges will require to be
equal in depth or distance between the flanges to the distance from the upper
surface of the central feather to the lowest curve of the wings against which the
lower flange is to be caught. After the lead glazing is folded down over the glass,
the one end of this girder-shaped bar may be inserted sheathwise into an end of
the core, and shoved along the saine and adjusted therein, so that the girder shaped
bar may be held fast in the core by the lower flange projecting to right and left
in the interior of the core under the wings, and the upper flange may rest or press
down upon the edges of the lead glazing, and prevent the same from rising off the glass.
The lower flange of the girder bar need not be male continuous along the length
of the girder, but may be discontinuously distributed at proper intervals along the
length of the girder.
Another form of cap may be made by folding longitudinally a strip of sheet iron
or other suitable metal into the form of a high arch in the centre, with two
horizontal flanges, one on each side. After the lead has been applied to the core,
and folded down over the glass, the arched portion of the cap is applied to and
shoved down over the central feather, and so as to cause the flat flanges on each
side to press upon the lead glazing and hold it down on the glass. The cap in this
case may be held in its place or secured to the central feather by pins passing
through both sides of the cap and through the central feather.
For the girder-shaped cap first above described cast-iron may be preferably used,
since the cap from its position in the bar is exposed to a compressive strain, such as
cast-iron is especially capable of resisting, and the girder bar may be most easily
constructed of cast-iron. For the form of cap in the second place above described,
sheet or hoop iron will in most cases be sufficient, and it is more easily manu-
factured, although in astragals of great length cast-iron may be preferable on
account of its great resistance to compressive strains.
My arrangements for enabling astragals with soft or ductile metal glazing
instead of putty to carry any number of overlapped sheets of glass in a vertical or
aloping position are as follows:-The two difficulties of retaining a number of
vertical or sloping sheets of glass, one overlapping another (or in the position
commonly known as slated), where lead or other soft ductile metal is used instead
of putty, is the tendency of the upper sheets to slide down and their liability to be
blown in, and these difficulties have hitherto prevented overlapped glass being used
in a vertical, or approximately vertical, or highly inclined position in connection
with the use of lead or other soft ductile metal as a substitute for putty. I meet
the first of these difficulties by passing pins of iron or other suitable material
through holes bored in the feathers or wings of the two astragals, in which the
sheet of glass is framed at such points that the pins when passed through the holes
shall support the sheet of glass above them; each sheet of the slated series being
supported at its lower corners by similar pins excepting the lowest sheet of all,
which is supported by the chair or bottom fixing which binds the two astragals in
which the sheets of glass are framed. The second difficulty before mentioned I
meet by inserting similar pins through holes in the feathers or wings of the two

page_text: astragals at such points that there shall be a pin on the inside of each sheet of glass
at or near each of its upper corners, so as to support it against the force of wind
or other external pressure on the surface of the sheet. These pins behind the top
corners of each sheet not only prevent the upper portion of that sheet from being
blown in, but also thereby and at the same time prevent the lower part of the
sheet above it from being blown in, seeing that the upper part of the lower sheet
is inside of the lower part of the upper sheet, which consequently cannot be blown
in so long as the upper part of the sheet below it is kept in its place against
external pressure by the pins behind its two upper corners. Where the sheets are
of great vertical length they may be supported not only at each of their upper
corners, but at one or more points below each of those corners.
These arrange-
ments dispense with the necessity of employing (except at the top and bottom
of the entire series of sheets) transverse framework to carry the upper and
under edges of each sheet, and permit the sheets to be slated, as in horizontal
or other roof glazing. These arrangements of pins below and behind each sheet
of glass can be used with any form of astragal, provided the material of the
astragal is strong enough to carry a number of vertical or highly inclined sheets
of glass slated one over the other, and rigid enough to retain the pins in their
holes.
When an astragal is used as a pillar or upright portion of the framework of the
building the outside surface of the glass at its side edges will rest against the
wings of the astragals, while the feather projecting inwards will separate the
-adjacent sheets of glass. In this relative_position of astragals and glass, the sup-
porting pin may either pass through the feather, each end of it supporting a sheet
of glass, and in this case the supporting pin will be in the same plane as the sheets
of glass, and its upper surface ought to be either flat or grooved that the glass may
rest securely on it; or there may be a supporting pin passed through each of the
wings to support corners of adjacent sheets of glass, in which case the pin must not
project inwards beyond the interior surface of the sheet which it supports. In
the before mentioned position of the astragal and glass relatively to each other,
the retaining pin must pass through the feather behind the glass, the ends of it
retaining the adjacent sheets of glass separated by the feather.
In end astragals, that is to say, where an astragal is fixed by the cross-hend or
web to the side of a pillar the feather projects parallel to the surface of the glass,
and the surface of the glass rests against the feather, the feather being outside.
In this case the retaining pin must be inserted into the wing or web at a point
behind the glass. The supporting pin may either pass through the feather at right
angles to the glass which it supports, or it may be inserted in the inner wing
immediately behind or inside of the feather and so as to lie in the same plane as
the sheet of glass, its upper surface being flat or grooved to give the glass a secure
hold. Whether the retaining pin passes through the feather, or is inserted in the
wing, it will lie behind the lead, and where there are a series of retaining pins
they will aid in holding the lead firmly down upon the glass, and preventing the
glass being removed by any one pressing open the leaden glazing from the outside.
In fact, glass with a series of pins behind it would be as secure as if puttyed.
The supporting pin in whatever way it lies always passes through the lead clothing
of the astragal.
When there are several vertical astragals used, each alternate astragal may be
formed with an inner flange or flanges parallel to the surface of the glass, and by
which the glass would be retained against wind or other pressure instead of by
pins; but for convenience of fitting in the glass the remaining astragals should
be formed only with outer flanges or webs, the glass being retained against
pressure of the wind by means of pins as before described, or by means of flange
pieces overlapping the glass or angled bars secured to the astragals after the glass
is inserted.
In some cases, as when the astragal is formed with a beaded feather the glass

page_text: may be retained against pressure from the outside by means of thin sheet-metal
spring clips or caps formed so as to embrace the feather inside the bead, and
having lateral wings which may bear against the inner surface of the glass or on
the lead fixing overlapping the inner edge of the glass. When no beading is
formed on the feather of the astragal, similar clips or caps may still be used to
retain the glass against outside pressure; but as the grip of the spring could not
in such case be relied on, I prefer to fix these caps or clips to the feather of
the astragal by means of pins passed through them and through the astragal
feather.