The rest of the story::: From Cessna History while building the 1952 Cessna 180..the following is from the first Cessna's 180 project pilot William D. Thompson in 1952.
In accordance with standard practice at the time (prior to 1952), the forward-facing fuel vent tube was mounted on the top surface of the wing. In a naive attempt to provide emergency venting with an ice-blocked tube, a small bleed hole was drilled on the aft side of the 900 bend. This hole, of course, was in the low pressure field of the wing, and later we found that, with the vent blocked, fuel would stream out the vent bleed hole and over the wing at a surprising rate. Another problem was the splashing of fuel out of the vent (with a full tank) during heavy braking deceleration in the landing roll. In another misguided effort, we incorporated a simple ball check valve assembly at the extremity of the tube. This only aggravated the accumulation of impact ice and the loss of fuel through the bleed hole.
Fortunately, not many pilots were flying in icing conditions in those days. However, one daring pilot selected the C-180 for a New York-to-Paris flight to commemorate Lindbergh's historic flight. He carried auxiliary fuel tanks in the cabin with a separate (and less vulnerable) fuel venting system. As related later, his standard fuel vent iced up over the Atlantic Ocean, causing a surprisingly high "apparent" fuel consumption when using standard fuel tanks. We had alerted him to this possibility before his flight. However, operation on his auxiliary fuel was normal, and he was able to proceed to Ireland instead of Paris.
That experience prompted us to search for a "protected" location for a fuel vent. After much flight testing, we found a behind-the-wing-strut location that essentially "hid" the vent in all flight attitudes, while, at the same time, providing the required positive pressure in the air space above the fuel. An additional requirement was another increment of pressure to promote sufficient "gravity" fuel flow in steep best-angle-of-climbs at minimum flying weight. As one can appreciate, this meant that the positioning of the fuel vent became very important both in production at the factory and at overhaul facilities In the field.
A final requirement was the prevention of fuel loss through the vent from fuel sloshing in rough air, or when parked on a sloping ramp. A simple flapper valve was placed in the vent line in each fuel cell that closed when fuel moved toward the vent outlet. To permit expanding fuel (heated from the sun after a refueling) to escape, a bleed hole was added to each flapper valve assembly. This hole also served as a siphon-break in the event of a malfunctioning (open) valve. This redesigned fuel vent system proved to be so effective that it has been used in all subsequent Cessna models that use strut-braced wings.