Crookes tube (X-ray generator)
front, is a metal tube. On the upper half of the instrument above the cube, there is a metal tube that narrows in diameter towards its top. The are several places that rubber vacuum tubes would attach to create a vacuum, two at the end of the glass cylinder, two at the end of the tube protruding from the top, and one directly attached to the main cube.
Functional Description: To operate the Crookes tube a voltage is applied between the metal electrodes at either end of the glass tube. The electric field produced by the application of a voltage causes the gas particles in the tube to accelerate and collide with other gas molecules. If the energy of the collision is high enough an electron will be forced off the gas molecule and a positive ion will form. This process of ionization will continue to occur as a chain reaction until most of the gas molecules in the tube have been ionized. The positive ions are then attracted to the negative cathode, and when the ions collide with the metal the electrons are removed from the surface. The voltage being applied to the tube causes the electrons to accelerate as they all move towards the positively charged anode at the other end of the tube. Due to the increased speed the electrons collide with the wall behind the anode which causes them to become excited. As the electrons become excited and return to their original energy level, x-rays are produced. The x-rays will then exit through the opening at the end of the metal tube which sits perpendicular to the glass tube. A sample can then be placed a certain distance away from the opening and when the x-rays hit the sample an image will be produced on a screen behind the sample.
Stand to tip Including glass tube length: 27.5cm
Glass tube length: 20.4cm
Glass tube circumference: 9.7cm
Outward facing tube diam.: 2.3cm
Outward facing tube length from stand: 10.6cm
History of the Object
Denning was born on September 3rd, 1916 in Fitchburg, MA to William Wallace and Emma McConnell Denning. His father was a research electrical engineer, and young “Rey” received much of his first knowledge from him. However, Rey’s father died in 1932, and him and his mother moved to Rochester, NY. It was here that Denning got his first taste of academia when he performed physics experiments with the faculty at University of Rochester while still in high school.
After high school, Denning obtained his BS in geology in 1939 from the Michigan College of Mining and Technology. From here, he briefly worked with the Army Corps of Engineers in Arkansas before accepting a teaching fellowship in mineralogy through Stanford University. In 1942, Denning married Helen Green, then very quickly after, traveled to South America. Denning worked in Bolivia during World War II, researching mineralogy and geology regarding the mining of tin. He afterward returned to Houghton to complete his M.S. degree, writing his thesis on sandstone. This dissertation was titled "The Petrology of the Jacobsville Sandstone, Lake
Superior." Denning then continued his Ph.D. (which he began during his time at Stanford) at the University of Michigan. Denning wrote his doctoral thesis on the hardness of diamond and was granted his Ph.D. in 1953. In 1956, Denning became an associate professor at the University of Michigan where he continued research on diamonds, mixing in various aspects of optics. Denning was granted his full professorship in Minerology, and taught at the University of Michigan until his death in 1967.
“Reynolds M Denning Memorial.” University of Michigan Faculty History Project. 2011, accessed 2/25/17.
Cloke, Paul L., and Edward H. Poindexter. "Memorial of Reynolds McConnell Denning." Mineralogical Society of America. March & April 1967. Accessed March 20, 2017. http://www.minsocam.org/ammin/AM54/AM54_609.pdf.
Spiegel, Peter K. "The first clinical X-ray made in America--100 years." AJR. American Journal of Roentgenology 164, no. 1 (1995): 241-243.
Crookes, William. "The Bakerian Lecture: On the Illumination of Lines of Molecular Pressure, and the Trajectory of Molecules." Philosophical Transactions of the Royal Society of London. Vol. 170. 135-164. 1878. Accessed March 20, 2017. http://rstl.royalsocietypublishing.org/content/170/135.
Dictionary of Scientific Biography, Edited by Charles Coulston Gillispie. Vol. 3. 474-481. NY: Charles Scribner's Sons, 1971.