Abstract: A system for determining the resistance of an electrolyte into which a conductivity probe is immersed, the system including a thermistor network, a probe or conductivity cell, and amplifiers all of which are so combined that the changes in electrolyte concentrations causing variations in resistance are measured with corrections being made for electrolyte temperature variation. The probe and thermistor networks control the feedback of the amplifier, and the probe and thermistor networks being arranged to adjust the output whereby the signal is in true proportion to conductivity.

Abstract: A device for facilitating the holding of reading material for easy reading, freeing the reader's hands for any desirable work. The device consists of an upstanding backing member against which the binding of the book or other reading material is supported and in combination with this backing, I provide a base support for the reading material. Upstanding from this base support is a spaced apart pair of page supports and cooperative with these upstanding members is a pair of biased fingers one being provided for each page support, these fingers being independently operable. The fingers are biased towards the page members. The device also includes means whereby the backing member, the reading material base support and the upstanding page supports are adjustable to vary the angle of the reading material relative to the horizontal. When the above mentioned members are adjusted to various positions, the biased fingers continue to be in releasable engagement with the page supports.

Abstract: An apparatus adapted for use in moving objects, such as mired vehicles, removing submerged or grounded boats from their mired condition and pulling them up on land to be repaired or loaded on trailers or the like, moving small buildings, etc. The apparatus is endowed with unusual versatility for it is adaptable to a great many uses. In many use circumstances the apparatus may be carried in a vehicle or the like for emergency use since it is composed of relatively few components so that under these circumstances it is in effect a portable kit. The components forming the apparatus may be easily set up into operative condition and operated by one person to perform its function. The puller apparatus comprises a fixed element which may be removably embedded in the ground in certain use circumstances and in other uses may be removably attached to a stationary member.