Astronomical and Physical Instruments
![.This is the 1231-B Amplifier and Null Detector. It has a height of 8 in.; width of 12.25 in.; and depth of 10.75 in. It weighs 23.75 pounds, including batteries. The amplifier has a built-in vacuum-tube voltmeter, which consists of a diode rectifier, a d-e amplifier, and the panel meter.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/GR%20amplifier%20and%20null%20detector.jpg?h=3aa48625&itok=NqBClrJO)
1231-B Amplifier and Null Detector
This apparatus was made by the General Radio Company. It is designed for use as a high-gain amplifier, as a sensitive null indicator for bridge measurements, and as a standing-wave indicator.
![This portable precision potentiometer comes in a wooden case with an instruction manual on the inner lid of the box. It contains 2 rheostats, a pointer galvanometer and a reflecting galvanometer.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/Rubicon%20portable%20precision%20potentiometer.jpg?h=a8451dc3&itok=gnV_pFnh)
Honeywell Rubicon Portable Precision Potentiometer model 2733
This apparatus was made by Honeywell Rubicon. This is a piece of electrical engineering test equipment from the early 1930's. It is a battery-powered precision potentiometer used for measuring low voltages (0-1.61 volts) very precisely.
![Potentiometer is comprised of a large metal box with several knobs on the top panel. These have labels such as: 'Aux EMF', 'Aux Pot', 'Galvanometer', 'range', 'SC', 'fine,' 'coarse, ' and 'GA sens.' An analog dial is labeled "Volt" and has a display of numbers that can be manipulated by turning the knobs. There are also two handles on both ends of the box. Instrument label includes Leeds & Northrup catalogue #7553 and serial number #1527443](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/K3%20universal%20potentiometer.jpg?h=515b10b0&itok=k84HbHqM)
Leeds & Northrup K-3 Universal Potentiometer
The potentiometer is used to measure voltages by comparison to a known reference voltage. The L&N K-3 universal potentiometer was the top-of-the-line research grade instrument used in industrial and university labs for best quality work.
![The Bygrave position line slide ruler comes in a yellow extendable cylindrical tube with altitude to azimuthal readings.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/Bygrave%20Slide%20ruler.jpg?h=4e469bdc&itok=CWE_GzkL)
Bygrave Position Line Slide Ruler
Bygrave Position Line slide ruler was used exclusively for navigation in the early 20th century. This particular model is a Mark IIA Bygrave slide rule developed at the air ministry of London circa 1930 by Captain L.C. Bygrave of the Royal Air Force.
![GP Keller Button Balance is placed in a sealed wooden cabinet with 2 front drawers to store weights. There are 2 glass sides of the cabinet for users to see the gold colored balance placed inside. There is a upward sliding glass panel on the front to be able to put weights inside on the bars of the balance.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/GP%20Keller%20gold%20precision%20balance.jpg?h=799ca939&itok=ktYZHuXa)
GP Keller Button Scale Balance
This was used to weigh gold "buttons" in assay offices. "Button" refers to the tiny speck of gold found in a sample of smelted ore, rather than a mechanical function of the balance. This instrument would have been used a precision balance in laboratories.
![The Alnor Pyrocon comes in a blue velvet lined black fitted carrying case along with a 14 inch long flex probe and an instruction manual.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/alnor%20pyrocon.jpg?h=d9386138&itok=PuCkl0CN)
Alnor Pyrocon type 4000A
Made by the Alnor instrument company, the Alnor Pyrocon is a multi-purpose portable temperature measuring instrument. It can measure temperatures of flat surfaces, plastic material and even fluids.
![Weston portable and switchboard shunt with 2 adjustable knobs on either side with bolts for connecting wire. Consists of a central label titled "5 AMP SHUNT 50 MV DROP" Along with the name of the company "Weston Electrical Instrument Company".](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/Weston%20AMP%20Shunt.jpg?h=54ec805e&itok=WrQkxid7)
Weston portable and switchboard shunt
Shunts are used as current bypass. It consists of one or many manganin conductors terminating copper blocks. This is a 50 millivolt drop shunt.
![A brass compass mounted on a wooden box.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/Compass.jpg?h=86134598&itok=JRr0xNfw)
Compass
A compass is used for navigation. It uses a magnetized needle which aligns itself to the cardinal North.
![The TYPE 602 Decade - Resistance Box is an assembly of two or more TYPE MO Decade -Resistance Units in a single cabinet. Mechanical and electrical protection of the units is provided by the shielded walnut cabinet and aluminum panel, which completely enclose both the resistance units and switch contacts.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/General%20Radio%20Decade%20resistance%20box%20Type%20602-K.jpg?h=9af2a9c0&itok=nIECyAvr)
General Radio Decade Resistance Box Type 602-K
Resistance boxes are constantly used in circuits where a wide range of resistance values is required. TYPE 602 Decade - Resistance Boxes can also be used as laboratory standards and as ratio arms for direct- and alternating -current bridges.
![Type 107-M Variable inductor has two coils, a rotor and a stator, mounted concentrically. As the position of the rotor is changed the coupling between the two coils changes and the inductance is varied. The coils are wound with stranded wire in which the separate strands are insulated from each other. The coils are impregnated and baked in a high -melting -point material before being securely mounted to the bakelite panel.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/General%20Radio%20Variable%20Inductor%20type%20107M.jpg?h=e0babd31&itok=VQc2g7tu)
General Radio Variable Inductor type 107-M
The TYPE 107 Variable Inductors are useful in the laboratory as standards of moderate accuracy for measurements of self- and mutual inductance, and as components of bridges, oscillators, and simi- lar equipment where a variable inductor is needed as a cir
![The K-2 potentiometer model 7552 has ranges of 0 to 1.61 volts, 0 to 1.161 volt and 0 to 0.0161 volt. The measuring circuit has 15 resistors of 5 ohms each with dial switch continuously adjusting slidewire of 5.5 ohms. The 3 current adjusting rheostats provide coarse, medium and fine adjustment of battery content. Comes with a polished mahogany case and cover.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/LN%20K-2%20potentiomete%20model%207552.jpg?h=d9386138&itok=QLoVFfOG)
Leeds & Northrup K-2 Potentiometer model 7552
The K-2 potentiometer model 7552 is a triple range precision potentiometer for general laboratory use. It has additional low range useful for thermocouple work and for checking industrial potentiometer pyrometers.
![This Leeds & Northrup Adjustable Mica Capacitor model 1058 has capacitance of 1 microfarad in five sections of 0..5,0.2,0.2,0.05 and 0.05 microfards. It has knife switch connections in various series and multiple combinations. It comes in a mahogany case with a cover.](/sites/physics/files/styles/landscape_col_lg_6/public/2023/images/LN%20laboratory%20standard%20adjustable%20mica%20capacitor%201058.jpg?h=d9386138&itok=hQkjsPXP)
Leeds & Northrup Adjustable Mica Capacitor model 1058
The Leeds & Northrup Adjustable Mica Capacitor model 1058 was made for high precision measurements. They can be used as standards of comparison in ac bridge measurements at commercial, audio and higher frequencies.