Porcelain Forestry Insulators

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The first forestry insulator was the "Victor" patented in 1889.  This is patent No. 403,491, which was assigned to the E. S. Greeley & Co.  However, the insulator in the patent does not appear to be intended to be used as a forestry insulator.  Greeley catalogs describe use for suspending telegraph and telephone lines from tree limbs, buildings, or use as a circuit break insulator.   Forestry insulators were used to suspend telegraph or telephone lines to fire lookout towers.  The use of fire lookout towers did originate before the National Forest Service was started in 1905, but doubt that communications with the fire towers was initiated much before the NFS.  From catalogs, it appears that forestry insulators became popular about the time the NFS was organized and especially in the 1910's to 1940's.

Note that most forestry insulators are interlocking.  That is, there is a projection that fits in a matching depression on the other half.  A different interlocking design can be found on OV-S (see ov20).  One of the smaller insulators, r1, does not have an interlocking design.  The mating surface of the two halves is smoothly glazed.  It is not uncommon to find a forestry insulator composed of two halves made by different manufacturers.  And it is not uncommon to find a forestry insulator with one half white and the other half brown.  Many of them are interchangeable.  All were made of dry process porcelain in 7 different basic types or styles.  However, there are at least 5 variations of the round type (see round).


From the 1889 E. S. Greeley & Co. catalog.

From the 1893 E. S. Greeley & Co. catalog.  At right is the only known specimen of the "Victor".  It is embossed on the top side edge above the wire groove: VICTOR and below the wire groove: PAT MAY / 14 89.

The Victor split tree insulator was popular for many years and was still being produced in the 1920's by various companies.  Here are two examples.


Thomas forestry insulator shown in 1901 Western Electric catalog.


Brunt forestry insulator shown in 1909-10 Electric Appliance Co. catalog.

I found several forestry insulators in Arkansas around 1987.

For a list of insulator related COMPANIES, click on the link.

To see images of forestry insulators in catalogs, click on the link.


Below is a list of more than 58 forestry insulators in my collection.  Please report any new ones you have.  The table describes each of the seven basic types.  Click on the Type to see a photo.  Markings and manufacturers are as follows:

BRUNT - G. F. Brunt Porcelain Co.; 1897-c. 1917 (East Liverpool, OH)

C in circle - unattributed

C. P. CO. - Cook Pottery Co.; 1897-1931 (Trenton, NJ)

D & S - Davidson & Stevenson Porcelain Co.; 1913-1920 (Newell, WV)

F - Findlay Electric Porcelain Co.; 1910-1927 (Findlay, OH)

FEDCO - Federal Porcelain Co.; 1917-1927 (Carey, OH)

G - unattributed
G. P. CO. - General Porcelain Co.; 1911-1927 (Carey, OH)

HP - unattributed but probably Akron High Potential Porcelain Co.; 1906-1910 (Akron, OH)

KNOX - Knox Porcelain Co.; 1923-1975 (Knoxville, TN)

MACOMB - Illinois Electric Porcelain Co.; 1910-1953 (Macomb, IL)

PERU - Peru Electric Mfg. Co.; 1892-?? (Peru, IN)

P. P. Inc. - Porcelain Products Inc.; 1927-1956 (Parkersburg, WV)

R. T. & S. Co. - R. Thomas & Sons Co.; 1884-1927 (East Liverpool, OH)

S & S - Smith & Stone, Ltd; 1920-?? (Georgetown, Ontario, Canada)

T or T in a circular impression - R. Thomas & Sons Co.; 1884-1927 (East Liverpool, OH)

THOMAS - R. Thomas & Sons Co.; 1884-1927 (East Liverpool, OH)

Triangle M - Illinois Electric Porcelain Co.; 1910-1953 (Macomb, IL)

VICTOR - unattributed, sold by E. S. Greeley & Co.


Type Description
OC Octagon
OV Oval
OV-1 Oval (one piece)
OV-S Oval with slotted ends
R Round with round hole
R-OV Round with oval hole
R-LOV Round with large oval hole

Click on link in the first column to see photos of each type of forestry insulator.

or click on this link to see three pages of photos of forestry insulators.


Photo Type Marking Marking Type Marking Location Color Condition
oc7 OC N-N (large hole)     white M
oc8 OC N-N (round octagon)     white VNM
oc9 OC N-N (small hole)     white VNM
oc10 OC N-N (thin glaze)     white NM
oc21 OC BRUNT embossed Top white VNM
oc20 OC C in circle / No. 22 embossed   white VNM
oc1 OC D & S embossed Btm white M
oc24 OC E P co embossed Top white VNM
oc2 OC F embossed Top white M
oc22 OC FEDCO embossed Top white NM
oc3 OC G embossed Top white M
oc4 OC G embossed Btm white VNM
oc25 OC H22 embossed Top lt blue M
oc5 OC HP recess-emb Btm white VNM
oc23 OC MACOMB embossed Top white VNM
oc6 OC MACOMB embossed Btm white M
oc11 OC P.P. 22 / U.S.A. (large marking) embossed   white M
oc12 OC P.P. 22 / U.S.A. (small marking) embossed   white M
oc13 OC 22 / P.P. Inc. embossed   white M
oc14 OC P.P. Inc. embossed Btm white NM
oc15 OC R. T. & S. CO. embossed Btm white NM
oc16 OC THOMAS embossed Top white VNM
oc17 OC THOMAS embossed Btm white VNM
oc18 OC TRIANGLE M embossed Btm white VNM
oc19 OC VICTOR / PAT MAY 14 89 embossed   white M
ov9 OV N-N     brown VNM
ov18 OV N-N     white VNM
ov17 OV BRUNT embossed Top white VNM
ov5 OV D-1 / TRIANGLE M (1/2 unit) embossed   white M
ov6 OV F embossed   white VNM
ov7 OV G. P. Co. embossed Btm brown VNM
ov8 OV KNOX / 6651 recess-emb   brown M
ov10 OV THOMAS embossed Top brown VNM
ov11 OV THOMAS embossed   white NM
ov12 OV THOMAS embossed Top white VNM
ov1 OV TRIANGLE M embossed Top brown M
ov2 OV 1 / TRIANGLE M (1/2 unit) embossed   brown VNM
ov3 OV 1 / TRIANGLE M // TRIANGLE M / 2 embossed   white DAMAGE
ov4 OV TRIANGLE M / D-1 embossed   brown VNM
ov13 OV U. S. A. embossed Top brown M
ov19 OV-1 N-N     white NM
ov22 OV-1 BRUNT recess-emb Top side white M
ov21 OV-1 FINDLAY recess-emb Top side white M
ov14 OV-1 THOMAS (marking on unglazed bottom) recess-emb Top side brown M
ov15 OV-1 THOMAS (marking on unglazed bottom) recess-emb Top side white M
ov23 OV-1 THOMAS (marking on unglazed bottom) recess-emb Top side brown M
ov16 OV-1 TRIANGLE M (3 firing rest teats) embossed Top white M
ov20 OV-S Triangle M / LM recess-emb Ends brown M
r1 R N-N     white M
r18 R C. P. CO. / 37 (1/2 unit) embossed   white M
r16 R PERU embossed Top white M
r2 R R. T. & S. Co. embossed Top white NM
r3 R T embossed Top white M
r17 R THOMAS embossed Btm white NM
r4 R TRIANGLE M / Y embossed   white M
r5 R-LOV N-N     white VNM
r7 R-OV N-N     white M
r15 R-OV CRANE / S & S MADE IN CANADA embossed   white VNM
r6 R-OV KNOX / 6539 recess-emb   white VNM
r8 R-OV P.P. 1049 recess-emb Btm white M
r9 R-OV T (in a circular impression) recess-emb Btm white VNM
r10 R-OV T (1/2 unit) recess-emb Top white NM
r11 R-OV T / MADE IN U.S.A. r-e / emb   white NM
r12 R-OV THOMAS embossed Top white VNM
r13 R-OV TRIANGLE M embossed Top white VNM
r14 R-OV TRIANGLE M / D-2 embossed   white VNM


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