National Mazda Daylight Blue Incandescent
Daylight blue lamps were introduced around 1914 to better simulate the colour rendering of daylight. Their development is attributed to Matthew Luckiesh, one of the greatest engineers of GE's National Lamp Works. The design was not patentable because decorative lamps had been made with a similar hue many decades earlier, but Luckiesh was first to recognise the value of pale blue glass for approximating daylight. He was responsible for introducing a full range of lamps for home and industrial use, and promoted them extensively as part of his research into improved lighting conditions, which led to him becoming known as 'The Father of the Science of Seeing'. They became very popular in shops, printing plants, cigar factories, laundries and homes.

The glass is naturally tinted with cobalt oxide to reduce the luminous flux of incandescent lamps by about 34%. This results in the absorption of yellow and red wavelengths and a modest increase in correlated colour temperature. The result is that most colours are rendered more closely to natural daylight than under ordinary incandescent lamps.

This example is one of the earliest daylight lamps. Its basic construction is the same as the ordinary 200W argon-filled coiled tungsten lamps that were first introduced in October 1914. The filament is bent into multiple V-shaped sections and only supported at one side, and can therefore only be burned in the vertical cap-up orientation. The first 200W lamps used large skirted caps at least until 1916, whereas this lamp has a small non-skirted cap and was therefore made at a later date. However the glass bulb has an evacuation tip on its crown, a process which was dropped after 1919. The stem marks identify its date as 1919.
Manufacturer: National Electric Lamp Works of GE, U.S.A.
Lamp Power: 200 Watts
Lamp Voltage: 105 Volts
Lamp Current: 1.90 Amperes
Cap Type: E26s/25 Brass + vitrite
Bulb Type: PS-95 PS-30 in eighths/inch
Bulb Finish: Daylight blue Natural coloured glass
Filament Type: C-7/3s Vee Wreath Vertical
Atmosphere: Argon-Nitrogen
Luminous Flux: 1850 lumens
Luminous Efficacy: 9.25 lm/W
Luminous Intensity: N/A
Beam Distribution: 100% Upward
Colour Temperature & CRI: CCT: 4100K CRI: Ra 96
Chromaticity Co-ordinates: CCx: 0.381 CCy: 0.389
Rated Lifetime: 750 hours
Burning Position: Vertical cap up
Overall Length: 213 mm 83/8 inches
Light Centre Length: 152 mm 6 inches
Factory: Ohio Lamp Plant, Warren U.S.A.
Date of Manufacture: September 1919 Date Code: L Z5 45
Original Value: US $3.00 (1916)
 
References: 1) The Electric Incandescent Lamp 1880-1925, E.J.Covington, publ. GE Lighting NELA Press, 1998, p.121
2) A Man from Maquoketa - A Biography of Matthew Luckiesh, E.J.Covington, publ. GE Lighting NELA Press, 1992, p.57
3) Makers of National - The Spirit and People of an Industrial Organization, E.J.Covington, publ. GE Lighting NELA Press, 1992, p.42
4) The Scientific Basis of Illuminating Engineering, P.Moon, publ. Dover Publications Inc, 1961, pp.170,489
5) Edison-Mazda Lamp Catalogue, USA, 1916, pp.6,8,9
6) GE Lamp Catalogue, USA, 1935, p.10
7) Photometric measurement