Mayday Mirror and ESM/I
[ Note: while I donate my rights as the photographer of this photograph to the public domain as CC0, the back of the red mirror at right is (c) 1987 by MM, and they have rights in that part of the image. I assert that my photograph of it here on this page is "fair use" in the USA as non-profit educational use, non-harmful to the rights holder's interests. However, if you wish to reuse this photograph, rights assessment for any such reuse is your responsibility. ]
The "Mayday Mirror", a stainless steel double-sided emergency signaling mirror approved by the US Coast Coast Guard (approval #160.020/11/0)
The Mayday Mirror is a 4"x5" double-faced stainless steel Emergency Signal Mirror (ESM) of the "rearsight" [1,2] type with a central cruciform aiming hole. The mode of operation and shape is that described in Figures 1-3 of the 1940s U.S. Patent 2,395,605 to Larry L. Young [3].
The Mayday Mirror is made in Canada, with the back marked "(c) 1987".
The Mayday Mirror (United States Coast Guard (USCG) Approval #160.020/020/11/0) is one of only four Emergency Signaling Mirrors (ESMs) with a current USCG approval in 2009 [4]. All but one of the four current USCG approved mirrors are of the rearsight type. The USCG specification for ESMs can be found online [5]. It seems likely that the USCG has approved no more than fourteen ESM designs since 1947 [4]. One current and three former USCG approvals are for ESMs with retroreflective ("Reflex") aimers rather than "rearsight" aimers.
The Mayday Mirror bears a marked resemblance to the tempered glass
American 1943 military issue ESM/1 mirror ( USCG Approval #160.020/020/1/0)[4] "cross-in-glass"[5] that was developed and manufactured by General Electric in World War II based on Larry Young's
concept. (See Figure 1: Mayday Mirror vs ESM/1 ) The ESM/1 was also to have been issued to Canadian troops in World War II [6].
Both the Mayday Mirror and the ESM/1 have a 4"x5" rectangular outline with rounded corners of approximately 7/8" radius. Both have a central cruciform aiming aperture with arms 5/8" wide. Both have a 1/4" diameter lanyard hole centered 0.5" from the edge of the mirror. Both have a circular reflective rear mirror centered on the aiming aperture, though the area of the Mayday Mirror rear mirror is smaller than that of the ESM/1 ( 1 13/16" diameter vs. a 2" diameter on the ESM/1, with some further effective reduction due to as little as 1 3/4" diameter due to
copyright text).
The aiming holes/windows in almost all ESMs/heliographs are of a circular shape. Of the scores of manufactured ESM designs I possess, the Mayday Mirror is the only one that has used a cruciform aimer since the 1940s ESM/1 and it's smaller sibling, the 3"x5" ESM/2. (I have seen one Canadian reference to putting a cross-shaped aiming hole in an improvised signal mirror [8], but usually a round hole is suggested.) The use of a round rear reflective surface smaller than the main front reflection surface is also very rare. Besides the ESM/1, ESM/2 and the Mayday Mirror, only the Chinese Air Force model has this feature [7].
Photographs of many Emergency Signaling Mirrors can be found on the Web [9,10].
[1] "Signaling with Mirrors: Reflex-Button Type of Mirror Adopted for Navy Survival", Naval Aviation News, 15 Sept 1944, pp. 32-33, which can be downloaded from the official government site here: [dead link]
[2] Hunter, Richard S., "Heliographic Signaling Mirrors", Air Se Rescue Bulletin
U.S. Coast Guard, NAVCG 128 VOL. Ill NO. 2, February 1946.
books.google.com/books?id=ZLJIAQAAIAAJ&pg=RA13-PA24
[3] Larry L. Young U.S. Patent 2,395,605 filed 12/7/1943
www.google.com/patents?id=pqVWAAAAEBAJ
(US patent law allowed filing up to 1 year after first public use.)
[4] Per 12/29/2009 search for Approval Series Name: "Emergency Signaling
Mirror-160.020" at the USCG web site:
cgmix.uscg.mil/Equipment/EquipmentSearch.aspx ;
and the hypothesis that the approval numbers were issued sequentially.
[5] USCG Approval Guidance for Emergency Signaling Mirrors
www.uscg.mil/hq/cg5/cg5214/survivalequip.asp#160.020
[6] Bi-Weekly Report No. 9 (Feb 12, 1944) of the Emergency Rescue Equipment
committee incuded minutes of the Dec 20 1944 meeting of the RCAF
SUBCOMMITTEE on EMERGENCY EQUIPMENT, which stated in part:
"Tempered Glass Signaling MIrror. This has been adopted
by the Canadians and will be packaged separately."
[7] Northern survival By Canada. Dept. of Indian Affairs and Northern Development.
Employment and Related Services Division, 1972
books.google.com/books?&id=GxshAQAAIAAJ
On page 80, in discussing a heliograph mirror, it says in part:
"The side of a ration can makes a good usable mirror. Carefully cut a cross about 1 inch long in the centre of the sheet with the point of your knife while the metal is laying on a flat surface."
[8] Chinese Air Force Pilot Survival Mirror (on Ebay 12/29/2009) [link now dead]
[9] My gallery of Emergency Signaling Mirror photos: [ Now a dead link - web host went out of business]
[10] History of development of US military signal mirrors
in WWII (lots of photos)
Mayday Mirror and ESM/I
[ Note: while I donate my rights as the photographer of this photograph to the public domain as CC0, the back of the red mirror at right is (c) 1987 by MM, and they have rights in that part of the image. I assert that my photograph of it here on this page is "fair use" in the USA as non-profit educational use, non-harmful to the rights holder's interests. However, if you wish to reuse this photograph, rights assessment for any such reuse is your responsibility. ]
The "Mayday Mirror", a stainless steel double-sided emergency signaling mirror approved by the US Coast Coast Guard (approval #160.020/11/0)
The Mayday Mirror is a 4"x5" double-faced stainless steel Emergency Signal Mirror (ESM) of the "rearsight" [1,2] type with a central cruciform aiming hole. The mode of operation and shape is that described in Figures 1-3 of the 1940s U.S. Patent 2,395,605 to Larry L. Young [3].
The Mayday Mirror is made in Canada, with the back marked "(c) 1987".
The Mayday Mirror (United States Coast Guard (USCG) Approval #160.020/020/11/0) is one of only four Emergency Signaling Mirrors (ESMs) with a current USCG approval in 2009 [4]. All but one of the four current USCG approved mirrors are of the rearsight type. The USCG specification for ESMs can be found online [5]. It seems likely that the USCG has approved no more than fourteen ESM designs since 1947 [4]. One current and three former USCG approvals are for ESMs with retroreflective ("Reflex") aimers rather than "rearsight" aimers.
The Mayday Mirror bears a marked resemblance to the tempered glass
American 1943 military issue ESM/1 mirror ( USCG Approval #160.020/020/1/0)[4] "cross-in-glass"[5] that was developed and manufactured by General Electric in World War II based on Larry Young's
concept. (See Figure 1: Mayday Mirror vs ESM/1 ) The ESM/1 was also to have been issued to Canadian troops in World War II [6].
Both the Mayday Mirror and the ESM/1 have a 4"x5" rectangular outline with rounded corners of approximately 7/8" radius. Both have a central cruciform aiming aperture with arms 5/8" wide. Both have a 1/4" diameter lanyard hole centered 0.5" from the edge of the mirror. Both have a circular reflective rear mirror centered on the aiming aperture, though the area of the Mayday Mirror rear mirror is smaller than that of the ESM/1 ( 1 13/16" diameter vs. a 2" diameter on the ESM/1, with some further effective reduction due to as little as 1 3/4" diameter due to
copyright text).
The aiming holes/windows in almost all ESMs/heliographs are of a circular shape. Of the scores of manufactured ESM designs I possess, the Mayday Mirror is the only one that has used a cruciform aimer since the 1940s ESM/1 and it's smaller sibling, the 3"x5" ESM/2. (I have seen one Canadian reference to putting a cross-shaped aiming hole in an improvised signal mirror [8], but usually a round hole is suggested.) The use of a round rear reflective surface smaller than the main front reflection surface is also very rare. Besides the ESM/1, ESM/2 and the Mayday Mirror, only the Chinese Air Force model has this feature [7].
Photographs of many Emergency Signaling Mirrors can be found on the Web [9,10].
[1] "Signaling with Mirrors: Reflex-Button Type of Mirror Adopted for Navy Survival", Naval Aviation News, 15 Sept 1944, pp. 32-33, which can be downloaded from the official government site here: [dead link]
[2] Hunter, Richard S., "Heliographic Signaling Mirrors", Air Se Rescue Bulletin
U.S. Coast Guard, NAVCG 128 VOL. Ill NO. 2, February 1946.
books.google.com/books?id=ZLJIAQAAIAAJ&pg=RA13-PA24
[3] Larry L. Young U.S. Patent 2,395,605 filed 12/7/1943
www.google.com/patents?id=pqVWAAAAEBAJ
(US patent law allowed filing up to 1 year after first public use.)
[4] Per 12/29/2009 search for Approval Series Name: "Emergency Signaling
Mirror-160.020" at the USCG web site:
cgmix.uscg.mil/Equipment/EquipmentSearch.aspx ;
and the hypothesis that the approval numbers were issued sequentially.
[5] USCG Approval Guidance for Emergency Signaling Mirrors
www.uscg.mil/hq/cg5/cg5214/survivalequip.asp#160.020
[6] Bi-Weekly Report No. 9 (Feb 12, 1944) of the Emergency Rescue Equipment
committee incuded minutes of the Dec 20 1944 meeting of the RCAF
SUBCOMMITTEE on EMERGENCY EQUIPMENT, which stated in part:
"Tempered Glass Signaling MIrror. This has been adopted
by the Canadians and will be packaged separately."
[7] Northern survival By Canada. Dept. of Indian Affairs and Northern Development.
Employment and Related Services Division, 1972
books.google.com/books?&id=GxshAQAAIAAJ
On page 80, in discussing a heliograph mirror, it says in part:
"The side of a ration can makes a good usable mirror. Carefully cut a cross about 1 inch long in the centre of the sheet with the point of your knife while the metal is laying on a flat surface."
[8] Chinese Air Force Pilot Survival Mirror (on Ebay 12/29/2009) [link now dead]
[9] My gallery of Emergency Signaling Mirror photos: [ Now a dead link - web host went out of business]
[10] History of development of US military signal mirrors
in WWII (lots of photos)