Anemometer use is constructed from a ping-pong ball attached to a string. When the wind blows horizontally, it presses on and moves the ball; because ping-pong balls are very lightweight, they move easily in light winds. Measuring the angle between the string-ball apparatus and the vertical gives an estimate of the wind speed. This type of anemometer is mostly used for middle-school level instruction, which most students make on their own, but a similar device was also flown on Phoenix Mars Lander. The first designs of anemometers that measure the pressure were divided into plate and tube classes. These are the
Measure S housing, that local labor be used on them, and incentivized developers for building near the city's subway lines. The city's business community, particularly developers, were as opposed to it as they were to Measure S. However, so was the CPLA. In a news release strongly opposing JJJ, it claimed that initiative had been "cooked up" by the interests opposing Measure S in an effort to split its support and keep it from the ballot. Measure S proponents said that they considered JJJ likely to fall short of its goals, pointing to what they considered broadly worded loopholes in JJJ. "Ultimately