Abstract: A method of measuring the heat conductivity of an object to be measured, comprising generating heat between the object to be measured and a heat resistant material, causing heat to flow through the interior of the object to be measured and the interior of the heat resistant material and obtaining the heat conductivity of the object to be measured from a temperature difference between at least two points of the heat resistant material, a heat conductivity measuring instrument using the same and a method of producing a heat insulating material.

Abstract: A method for measuring the amount of direct solar radiation and an apparatus according to the method. The invention provides a light sensor which rotates at a constant speed while scanning the sky including the sun. The differential coefficient of the radiation received is obtained from the output of the light-receiving element, thus substantially eliminating the scattered light component from the output. The preferred embodiment of the light-receiving element is a pyroelectric detector.

Abstract: An improved thermopile is provided. A plurality of thermocouples constituting the thermopile are composed of segments of one metal and segments of the other metal, and the segments of different metals are connected to one another alternately so that the thermocouples are arranged in series on a heat-resistant, electrically non-conductive substrate. Each segment has a portion plated on one surface of the substrate, a portion plated on the other surface of the substrate and a portion plated on the inner wall of through holes formed in the substrate to connect the two portions plated on the two surfaces of the substrate with each other. The thermopile is prepared advantageously by utilizing plating and photo-etching techniques.