Abstract: The saw table guide bar has magnets thereon so that when it is inserted into the slot in an iron saw table it is urged to slide along the side of the slot. The magnetic saw table guide bar is used to support various measuring devices and overcomes measuring difficulties resulting from table slots of varying width.

Abstract: The caliper gauge has a V-shaped gauge body. The V-shaped gauge body has stepped pairs of measuring surfaces both externally and internally of the V-shaped gage body. The pairs of measuring surfaces are a known distance apart for setting external and internal calipers. The gauge body may rest against a back plate, which prevents the caliper from being dislodged from the measuring surface. Indicia are provided for both the external measuring surfaces and internal measuring surfaces on the gauge body.

Abstract: The gage has a body made of flat plate which has a reference edge. Another edge is a gage edge which is angular and defines a sharp apex away from the gage edge. A foot is slidable along the gage edge to rotate the gage body around the sharp apex pivot. Indicia indicate the angle at different foot positions.

Abstract: The measuring gage has a body which is positioned in the upright direction for vertical measurement or can be positioned in any direction for other measurements. The body includes a notched land area for nesting a ruler which is locked in by rotatable stops to restrict ruler movement. A further recessed area within the ruler land area houses a strip magnet to hold the ruler. Two half-round configurations simulate vertical rods which serve as ways upon which the measuring arm and protractor housing ride. A T-shaped slot between the half-round rod ways acts to retain a nut for the measuring arm. The measuring arm can glide along the body and measure the height directly against the ruler. The magnetic strip retains the ruler in its nested area when the gage body is in a vertical position and unsecured by the cam locks.

Abstract: A method of and apparatus for the presence of a target species in a sample taken from or consisting of a mixture of species, comprising the steps of introducing one or more electrical diodes into the mixture prior to taking the sample from the mixture, in such a manner that the presence of diodes in the sample is dependent on the presence of the target species in the sample; passing an alternating electrical signal having a known waveform through the sample; and detecting the modification of the waveform of the signal emerging from the sample due to the presence of the diode or diodes in the sample.

Abstract: The body of the gage is in the form of a channel with web and flanges. The web and flanges define three planar surfaces with the flange surfaces at a right angle to the web surface and parallel to each other. The edges define an orthogonal structure. An angle gage movably mounted on the body defines angles with respect to one of the orthogonal surfaces and a height gage on the body measures distances with respect to the same orthogonal surface.

Abstract: A folding door for industrial use utilizes a curtain having a series of spaced-apart panel sections which are insulated, and one or more folding hinge sections spanning adjacent panel sections. The hinge sections are generally made of flexible sheet material thinner than the insulated panel sections. Such a curtain is suspended from a doorway, and is opened and closed by folding and unfolding the curtain around the hinge sections. The folding door of the invention is particularly advantageous for use in large industrial refrigerators and freezers.