SonTek / YSI (Popularity: )

Makes water velocity measurement sensors - ADCP/ADP acoustic doppler current profilers, ADV velocimeters, DVL speed ...
Category: Science\Earth Sciences\Oceanography\Products and Services

Testo (Popularity: )

Temperature, humidity, air velocity, flue gas analyzer and pH logging devices.
Category: Science\Instruments and Supplies\Laboratory Equipment\Data Loggers and Recorders

Relativity and waves (Popularity: )

Relativity explained by waves. A well animated program on waves will show you the laws ...
Category: Science\Physics\Relativity\Alternative