By Tom Iannelli Walk along any rail line in Ontario and you'll still see
the last generation of telegraph line insulators suspended on
aging wooden telegraph poles
Fiber optics and laser communications systems terminated
the age of the telegraph, which was the king of Canadian communications
for 150 years. If you look up at these insulators, regardless
of their shape or colour, they'll all
have one thing in common - they are threaded.
Railroads began springing up in Upper Canada and Canada East
in the 1840's. Trains were controlled by signalmen with flags,
which, as you can imagine, was a terribly inefficient way to
move trains through the ever growing population of the booming
The United States railroads adopted a number of electronic
signal systems and Canada soon followed suit. The Montreal Telegraph
Company was formed in the 1840's and by the 1850's was established
as one of the pioneer railroad signal companies.
While private telegraph companies existed, it was the railroad
that needed hundreds of miles of signals. Open metal wire will
transmit a signal over a relatively long distance until the weather
turns wet, foggy or snowy at which time the signal quickly grounds
out and disappears. This type of weather is sometimes encountered
in Canada and an insulator is required. Glass is the perfect
non-conductor of electricity and so the practice of insulating
the metal wire from the wooden pole was born.
The earliest railroads and telegraph companies in Canada
simply purchased their insulators from the already established
The earliest insulators were simple affairs of glass, designed
to sit loosely upon a wooden pin and thereby suspend the transmission
wire in mid air, keeping the wire away from the wooden pole.
In this manner, transmission would occur even on wet days when
the signal would normally be lost.
Urban tales abound of broken bottlenecks being used as the
earliest insulators but there is little, if any, evidence to
support these ridiculous tales.
The earliest commercially produced insulators were designed with
a tapered pinhole that was smooth in nature, hence the term threadless.
The pinhole was designed to sit upon a matching smooth tapered
wooden pin. The glass insulator was then pitched or tarred to
the pin to keep it in place, and the transmission wire was tied
with a small metal tie wire to the side of the insulator. This
was a simple system, and yet was somewhat effective.
It improved transmissions remarkably on wet days but the
system had a major flaw. Pitch (or resin or tar) contracts and
hardens in cold weather at a very different rate than glass contracts,
and so in cool weather the pitch would crack free of the glass
and the glass insulator would pop free of the tapered wooden
pin. The insulator would soon be dangling uselessly in mid-air
prompting constant repair to the line.
It was not unusual to have a track repair shack every three
miles in Ontario, since a linesman would be required to walk
his three mile section of track every day to keep the lines in
Canadian threadless insulators were produced in a number
of unique styles over the years and were manufactured on the
east coast of Canada during the 1840's &SHY; 1860's, at a site
in Quebec into the 1870's, and in and around Hamilton, Ontario,
until late in the 19th century.
A new generation of insulators was invented in 1865 &SHY; the
threaded insulator. This modern version was manufactured with
a threaded interior cavity, which was then turned securely onto
a matching threaded wooden pin. The advantages of this system
were obvious, no longer would the insulators pop free of their
pins and the inefficient tar/pitch method was dropped from service
by 1880. The insulators that can still be seen along the railroads
of Canada are direct descendants of this type &SHY; they are
all threaded and locked to their support pins.
As the "new" generation of threaded insulators came
onto the market in the late 19th century, the old threadless
lines fell into disrepair. Many were allowed to rot and fall
over, some were dismantled and the insulators either buried,
thrown out or melted down and recycled. The process of removing
the old threadless insulators was never delicate &SHY; since
they were glued in place the linesman merely struck the base
of the insulator to break it free of the pin. Hence, almost all
threadless insulators encountered today have chipped bases.
Canadian Threadless Styles:
There is some overlap in early Canadian and American insulator
styles, but many styles are uniquely Canadian.
Figure (1) shows a threadless Canadian Wade insulator named after
its American inventor Jeptha Wade. This is one of the earliest
styles in Canadian threadless insulators and these simple pieces
are unembossed and are valued at roughly $500. They are known
to exist only in varying shades of aqua and green. Several of
these primitive pieces were uncovered recently in Toronto during
Figure (2) shows the one of the
most commonly encountered Canadian threadless and these styles
show up in varying shades of green and aqua, both unembossed
and embossed. If embossed they typically read "M.T.Co."
indicating the Montreal Telegraph Company. In mint condition
they retail for $100 to $150 on average. In a deep purple colour
they would sell for closer to $1,000.
Figure (3) shows two early blackglass
threadless pieces that are both embossed "Foster Brothers,
C.E., 1858". The "C.E." is Canada East. In mint
condition these pieces retail out at $300 typically. These pieces
typically show up in varying shades of dark aqua &SHY; black.
Figure (4) shows two very small threadless pieces that were actually
designed for service in British Columbia. They are
embossed "McMicking, Victoria B.C. 75" and are named
after their designer. A cache of thousands of these threadless
insulators was discovered in the 1970's in British Columbia and
they flooded the North American market. Even though threadless,
they now typically sell in the $50 range even if in mint condition.
Again, urban tales abound about these insulators being used by
the native peoples of western Canada for drinking glasses, with
little proof to support these fables.
Coincidentally, the author of this article grew up on McMicking
Street, also named after this early pioneer in the Canadian telegraph
and electrical industry!
Figure (5) shows a primitive style
of threadless insulator that comes in a large array of colours
and swirls. This "egg" variety is unembossed and can
range in price from $300 to much higher depending upon the colour.
They are typically seen in aqua and light blue but the photo
also shows a more desirable jade-milkglass version on the left.
Finally, Figure (6) shows a series of three Canadian threadless
beehives. These Canadian pieces were very popular in the late
1800's and in fact the molds were simply reworked and threaded
when the concept of threading was invented. It is possible to
find nearly identical beehives, produced in the same mold, which
are threaded and threadless. These styles, unembossed and typically
aqua in colour, are hard to find in pristine condition. Basic
aqua pieces start at $300. This is a truly Canadian insulator
since this style was never produced south of the border.
Pricing and Rarity of Canadian Threadless:
Pricing of insulators is dependent upon rarity and condition.
Unfortunately, very few threadless are found in pristine condition.
Bottle collectors do not want bottles with their necks broken
off insulator collectors in turn do not want insulators that
have been hit by a shotgun blast.
Truly rare threadless pieces, in pristine condition, in rare
colours such as cranberry or purple, will demand higher prices
that those shown in this article. Note however, that purple threaded
insulators are not particularly rare since they were mass-produced
well into the 1940's.
Most threadless insulators such as the "M.T.Co's"
and "McMickings" are easily found at antique shows
and do not demand premium prices. Wire groove chips and any sort
of base damage (chips, flaking, fractures) will effectively remove
90% of the book value of the insulator.
The other damaging factor to threadless insulator pricing
is the field of reproductions and commemoratives. Most commemoratives
are marked with a manufacturers code such as "NIA"
or "LSV" and most have a year of production stamped
onto them such as 1995. These are easily spotted.
However, cases of legitimate commemoratives being bored out
or having the initials ground off do pop up every year. And,
as with bottle collectors, unscrupulous dealers are now irradiating
insulators to force them into weird and wonderful colours that
are not natural. How can you tell the altered or fake piece from
the real threadless beauties? Sometimes you can't.
It is definitely buyer beware!
1 - Most threadless insulators are naturally blue, aqua or green.
Weird colours should be viewed with suspicion.
2 - Threadless insulators have a tapered pinhole that is wider
at the bottom than at the top. If a modern insulator has been
drilled out the new pinhole will probably be straight from top
3 - Has the base or dome been ground or polished? If so, what
was removed? Be suspicious of this since modern logos may be
removed and polished with a bit of work.
4 - Is the insulator too light? Filling in the missing pieces
of insulators with resin makes them effectively worthless.
5 - Does the insulator seem too good to be true? It probably
Other Threadless Glass Things:
Literally hundreds of other glass items are mistaken for true
threadless pin-type insulators. The true collector has little
interest in the following items, which appear to be threadless,
but were never designed to be used to carry telegraph lines:
6 - Electric fence insulators. Often small, sometimes the pinhole
pierces the top of the insulator, sometimes it doesn't. These
have little value.
7 - House or attic insulators. Usually very small. Little value.
8 - Lightening rod insulators. These come in a variety of shapes
and sizes. Sometimes the pinhole pierces the dome of the insulator,
sometimes it doesn't. These have some collectible appeal and
sell in the $5 - $50 range,
9 - Wall tubes, used to pass wiring through thick walls. These
are hollow glass tubes and range from very small to vary large,
but have little value.
10 - Model T automobile ashtrays! These turn up at auction all
the time as threadless insulators and in fact they are not insulators
at all, even though they look like threadless insulators. They
always have a small hole on the side, and are usually multi-coloured.
They usually sell to car-buffs for $40 - $50.
11 - Battery Rests. These look like little doorknobs or "birdfeeders"and
were designed to suspend the batteries that powered the telegraph
line from the work table, to prevent the telegrapher from being
shocked. They were also used on the bottom of the telegrapher's
chair for the same reason. They are usually aqua or light green
in colour. Many are embossed with company names or "ESB".
Many varieties exist and they sell in the $10 - $100 range.
12 - Guy Wire Strains. These egg-shaped creatures are often mistaken
for threadless insulators and were in fact used on the wires
erected on the sides of poles to keep the poles from tipping
over. They come in many shapes and colours and have no great
My Final Collector's Comments
Probably every Canadian has had a glass insulator in a window
in their house at some point in their life. If you still have
one there, then you have an interesting piece of Canadian history
since they are not manufactured in Canada any longer, and it
isn't likely that the telegraph will make a roaring comeback
any day soon.
If you are lucky enough to have a threadless insulator in your
window, then you have a piece of early Canadian history that
dates from the earliest days of our Confederation.