The Aerodynamic Research on Windmill Sails of Poul la Cour, 1896–1900 - Wind Power for the World: The Rise of Modern Wind Energy - page 100

Figure 4.7 Drawing of a gas lamp (left); section (right).

The two gases go through pipes to a little chamber, where they
are mixed and pressed through a pipe and ignited. The flame itself
does not give much light (pale blue/white), but is very hot. The
flame is heating a small ceramic object, which contains zirconium.
It gives a very strong bright white glowing light. Hydrogen, how-
ever, did not find general application for lighting in the following
years. The electric light bulb was preferred.
The installation functioned for seven years from 1895 to 1902.
It is important that this success released more financial support
and made it possible to continue the research as the State Experi-
mental Wind Laboratory with Poul la Cour as director.

4.4 An Aerodynamic Surprise

Millwrights were excited because a new market had appeared:
the production of electricity from windmills. One millwright,
Christian Sørensen from Skanderborg, contacted Poul la Cour
in 1896. Sørensen had invented a new design of windmill rotor,
the conical wind catcher (Keglevindfanget), and he asked la Cour
for help to produce documented test results in order to seek a
patent. Sørensen himself had started research on models with
diferent rotor types—all with same diameter—in front of a
barrel with a blowing ventilator in one of the open ends. It was
called a blowing cylinder (blæsecylinder) and possibly it was the
first experimental wind tunnel. Until then windmill rotors most
often were tested on a rotating merry-go-round (carousel) arm.