Abstract: A method and apparatus for detecting orientation with respect to predetermined frames of reference particularly for use in aligning vehicle headlamps relative to frames of reference such as the true horizontal and the longitudinal axis of the vehicle. Orientation relative to the true horizontal is detected by comparing the electrical responses of two photocells which have a peak spectral response at a predetermined wavelength and which bracket a gas bubble provided in an upwardly curved transparent housing containing both the bubble and a fluid. The photocells are illuminated through the housing by associated light emitting diodes which have peak emissivities at wavelengths matched to the peak spectral response of the corresponding photocells.

Abstract: A system for monitoring the condition of a plurality of fluids as determined from measured electrical characteristics of samples of the fluids which are successively applied to a sensor. The system includes a remote test terminal having a remote controller and associated memory, a data entry device and display, and a test module. The test module includes the sensor and a coupled electrical circuit for generating a test signal representative of the electrical characteristics of a fluid sample applied to the sensor. The remote controller is responsive to a user operation at the data entry device to generate and store sample identification and period of use signals in the memory for each sample applied to a sensor, and to also control the test module to generate the test signal for the sample and to store that signal in the memory in conjunction with the sample identification and period of use signals.