Ionospheric Section Records, 1927-[1959] (Bulk 1942-1946)
Carnegie Institution of Washington
Department of Terrestrial Magnetism Archives
Washington, DC
Finding aid written by:
Jennifer Snyder
August 2005
Ionospheric Section Records, 1927-[1959] (Bulk 1942-1946)
Table of Contents
|
Page |
|
Introduction |
1 |
|
Historical Note |
1 |
|
Scope and Contents Note |
2 |
|
Folder Listing |
4 |
|
Subject Terms |
10 |
|
Bibliography |
11 |
|
Ionospheric Section Records, 1927-[1959] (Bulk 1942-1946)
Introduction
Abstract: This collection documents the work conducted by the ionospheric program at the Carnegie Institution�s Department of Terrestrial Magnetism.
Extent: 17 linear feet: 12 records center cartons, 1 oversize records center carton, 2 flat storage boxes
Acquisition: The records have been in the possession of Department of Terrestrial Magnetism (DTM) since their creation.
Access Restrictions: There are no access restrictions. Authorization for declassification is noted in a memorandum of the Acting Secretary of Defense, 2 August 1960.
Copyright: Copyright is held by the Department of Terrestrial Magnetism, Carnegie Institution of Washington. For permission to reproduce or publish please contact the archivist at the Department of Terrestrial Magnetism.
Preferred Citation: Ionospheric Section Records, 1927-[1959], Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, D.C.
Processing: Processing was completed by Jennifer Snyder in August 2005.
This collection was processed through the generous support of the National Historical Publications and Records Commission.
Historical Note
*Dr. Louis Brown wrote an excellent history of the Ionospheric Section which is found in Centennial History of the Carnegie Institution of Washington, Volume II: The Department of Terrestrial Magnetism. Much of the below information has been cribbed from this chapter.
Ionospheric research began at the Department of Terrestrial Magnetism (DTM) in 1924 when Gregory Breit joined the staff. The initial goal of the program was to establish the existence of a conducting layer (then called the �Kennelly-Heaviside Layer�) in the upper atmosphere which allowed radio transmissions to travel great distances. Merle Tuve was brought on board shortly after Breit. Together they developed a technique for transmitting modulated radio signals up into the atmosphere and oberving the resulting radio echoes. The echo observations proved the existence of ionosphere and permitted measurement of its height.
In the early 1930s, Odd Dahl and Lawrence Hafstad joined the program to continue the ionospheric studies until work was transferred to the National Bureau of Standards (NBS). However, NBS programs were curtailed due to the Depression, and with the arrival of Lloyd V. Berkner at DTM in 1933 the Department�s ionosphere program resumed an active phase. Under Berkner, new automatic ionospheric recorders were developed and a field station for experiments established at Kensington, Maryland. Berkner brought a national and international scope to the work because of his involvement in many organizations. Harry W. Wells was acting chief of DTM�s ionospheric work during the War years.
During World War II, DTM established ionosphere stations around the globe to facilitate communication among the armed forces. Carnegie was an integral member of the Wave Propagation Committee (WPC), organized under the Joint Communications Board, Joint Chiefs of Staff. According to the National Institute of Standards and Technology�s museum website,
In 1942, the Combined Communications Board of the Combined Chiefs of Staff in Washington, DC created the Interservice Radio Propagation Laboratory (IRPL) and placed its headquarters at NBS. The duties of this new lab were:
� to centralize and disseminate all ionospheric and radio propagation data for the U.S.
� to operate and sponsor operation of such ionospheric stations as were necessary to obtain the data
� to cooperate and collaborate with the radio propagation organizations of other countries of the United Nations
� to issue radio propagation information and predictions for the use of the armed forces and other cooperating agencies of the United Nations
� to train personnel of the armed forces in the use of ionospheric and propagation data
� to make special propagation studies and solve specific problems upon request
IRPL later became the Central Radio Propagation Laboratory (CRPL). Indeed, these were much the same duties of the Carnegie program.
After the War, DTM�s ionospheric activities moved to its new experimental laboratory at Derwood, Maryland. In the 1950s the focus of research there gradually shifted to radio astronomy. �Upper atmosphere research� was mentioned prominently in the Carnegie Year Book for the last time in 1957. With Wells� departure in 1960, ionospheric research at DTM effectively came to an end. [An excellent summary of DTM�s ionosphere activities during the War is given in Year Book 45, pp. 54-56, 1946.]
Scope and Contents
This collection documents the work conducted by the ionospheric program at the Carnegie Institution�s Department of Terrestrial Magnetism. It includes committees meeting minutes and transcripts, data collected at Carnegie�s observation stations, and research notebooks documenting various experiment conducted to establish the existence of a conducting layer for radio waves in the upper atmosphere.
Arrangement
This collection is arranged in three series as follows:
Series 1: Files, 1934-1948, n.d.
Series 1, Subseries 1: Equipment files, 1936-1946, n.d.
Series 1, Subseries 2: Federal Communication Commission (FCC) files, 1934, 1938-1946, n.d.
Series 1, Subseries 3: Interservice Radio Propagation Laboratory (IRPL) files, 1942-1946
Series 1, Subseries 4: Ionosphere Station Reports, 1941-1946
Series 1, Subseries 5: Wave Propagation Committee (WPC) files, 1942-1946
Series 1, Subseries 6: Miscellaneous files, 1936-1948, n.d.
Series 2: Data, 1933-1956 [bulk 1933-1946]
Series 3: Research Notebooks, 1927-1950s
Series 1: Files, 1934-1948, n.d.
This series is arranged into 6 subseries, organized by file type (e.g., committee). The types of materials found in this series include: regulations, handbooks, mimeographs, and correspondence.
Series 1, Subseries 1: Equipment files, 1936-1946, n.d.
The equipment files document the types of equipment used at observation stations. Files may include instructions, manuals, or other documentation.
Series 1, Subseries 2: Federal Communications Commission (FCC) files, 1934, 1938-1946, n.d.
This subseries contains Carnegie�s FCC documentation. Of note is the application file for establishing a radio station in College, Alaska.
Series 1, Subseries 3: Interservice Radio Propagation Laboratory (IRPL) files, 1942-1946
This subseries documents the activities of IRPL. Established by the National Bureau of Standards, this organization was responsible for collecting radio-wave propagation data and disseminating them to the armed forces.
Series 1, Subseries 4: Ionosphere Station Reports, 1941-1946
This subseries contains reports from Carnegie Institution run stations around the world. They are organized by country.
Series 1, Subseries 5: Wave Propagation Committee (WPC) files, 1942-1946
This subseries contains agendas, minutes, notes, and other communications about the meetings of this committee. Abbreviations on the files are as follows:
WP = Wave Propagation
JX = Joint Communications Board
JCB = Joint Communications Board
CX= Combined Communications Board
CCB= Combined Communications Board
Series 1, Subseries 6: Miscellaneous files, 1936-1948, n.d.
The files in this subseries are more general than those found in the above subseries. Reprints, reports, and bulletins from Carnegie and external sources are included here. Of particular note is the photograph album which was created by/for H.W. Wells; it illustrates wartime operations and equipment at DTM�s ionospheric stations. Also noteworthy are the first motion pictures of ionospheric activity, produced at DTM in 1946 using panoramic recorders. Other films document field work at DTM�s observation stations. The films that are in their original cardboard boxes were made at observation stations and show people working.
Series 2: Data, 1933-1956 [bulk 1933-1946]
This series contains observation logs, charts, and traces (ionograms) from observation stations around the world. Of note in this series are auroral materials from College, Alaska. The records are arranged geographically and then by type of material.
Series 3: Research Notebooks, 1927-1950s
Several of the notebooks in this series are believed to be associated with Tuve and Breit�s ionosphere experiments, though no personal identifiers have been found with the notebooks. Two notebooks belonged to H.W. Wells and are identified as such.
Folder Listing
|
Box |
Folder |
Series 1, Subseries 1: Equipment files, 1936-1946, n.d. |
|
|
Description of 12-inch Indicator Supplied with Navy No. 2 Equipment, 1945 |
1 |
1 |
Antenna System, 1942-1945 |
4 |
1 |
Auroral Camera, 1941 |
1 |
2 |
Automatic Voltage Controller, 1941-1943 |
|
3 |
British Equipment, 1942-1945 |
4 |
2 |
Communications Equipment, 1937 |
1 |
4 |
Diesel Engines, 1936 |
|
5 |
Huancayo Magnetic Observatory Diesel Folder, 1940 |
|
6 |
Watheroo Magnetic Observatory Diesel Folder, 1939 |
|
7 |
Duplex Ionospheric Recorder No.1, LVB [Berkner], n.d. |
|
8 |
Duplex Ionospheric Recorder No.2, LVB [Berkner], n.d. |
|
9 |
Fixed-Frequency Equipment, n.d. |
|
10 |
A Tracking System for Ionosphere Measuring Equipment, 1945 |
|
11 |
Ionospheric Equipment, 1933-1936 |
4 |
3 |
C.T. Kwei Equipment, 1937 |
1 |
12 |
Preliminary Description of Manual Multifrequency Standby Equipment, DTM model No. 2, 1944 |
|
13 |
Manual Multifrequency Ionospheric Recorder, Model 1, 1945 |
|
14 |
Manual Multifrequency Ionospheric Recorder, Model 2, 1945 |
|
15 |
Manual Multifrequency Ionospheric Recorder, Extra MS and prints, n.d. |
|
16 |
Report: Manual Multifrequency [Ionospheric] Recorder, DTMCIW Model 2, 1945 |
|
17 |
Manual Multifrequency Ionospheric Equipment, Model 3, 1946 |
|
18 |
Manual Standby Equipment, 1944-1946 |
4 |
4 |
Instruction Book: Navy Models DAB and DAB-1 Radio Direction Finder Equipment, 1943 |
1 |
19 |
Panoramic Ionospheric Recorder, Model 2, H.W. Wells, 1952, n.d. |
|
20 |
Portable Buildings, 1942 |
|
21 |
Power Plants, 1943-1944 |
|
22-23 |
Power Supply Equipment, 1936-1938 |
|
24 |
Power Supply Factory Data, 1939-1940 |
|
25 |
Watheroo Magnetic Observatory Power Supply, 1924, 1931, 1934 |
|
26 |
[General Instructions for Operation of Special Radio Transmitting and Receiving Equipment for Determining Heights of Ionized Regions of the Upper Atmosphere], 1933 |
|
27 |
Visual Recorder [Magnetograph], 1942, 1944 |
|
28 |
|
|
|
Series 1, Subseries 2: FCC files, 1934, 1938-1946, n.d. |
|
|
College Alaska Station [Application for Station], 1941-1946 |
1 |
29 |
The Communication Act of 1934, 1942 |
|
30 |
Data [regulations and other papers], 1938-1939 |
|
31-32 |
Master Frequency List of Allocated, Assigned, and Received Frequencies, 1943 |
|
33 |
Mimeographed Sheets [memoranda, press releases, and other papers], 1938-1946 |
|
34-35 |
Publications, 1940, 1942, 1944, 1945 n.d. |
|
36 |
Rules and Regulations, 1934, 1939 |
2 |
1 |
Study Guide and Reference Manual for Commercial Radio Operator Examinations, 1939 |
|
2 |
|
|
|
Series 1, Subseries 3: Interservice Radio Propagation Laboratory (IRPL) files, 1942-1946 |
|
|
B: Frequency, 1942 |
2 |
3 |
C: Conference report, 1944 |
|
4 |
D: Basic Radio Propagation Predictions Three Months in Advance, 1946 |
|
5 |
F: Ionospheric Data, 1944-1946 |
|
6-9 |
G: Correlation of D.F. [Direction Finder] Errors with Ionospheric Conditions, 1945 |
|
10 |
H and M: Frequency Guide for Operating Personnel, 1943-1944 |
|
11 |
J: Weekly Forecasts, 1946 |
|
12 |
K: Best Radio Frequencies � Atlantic, 1942-1945 |
|
13-14 |
R: Nomograms for General Long-time Frequency Allocation, 1943-1945 |
|
15-17 |
T2a: Low-level coverage of Radars as Affected by Weather. Procedures and Charts, 1944 |
|
18 |
Average F and F2 Critical Frequencies and 3000km MUF Factors, 1942-1944 |
|
19 |
High-Frequency Radio Transmission Conditions, 1941-1943 |
|
20-21 |
MUF Graph Paper, 1943 |
|
22 |
Optimum Frequency Charts for Merchant Ships, 1943 |
|
23 |
Radio Propagation Conditions, 1943-1944 |
|
24-25 |
Radio Propagation Handbook: Part 1, 1943 |
|
26 |
Radio Propagation Handbook: Drafts, 1942-1943 |
|
27 |
Radio Propagation Handbook: Drafts, 1942-1943 |
3 |
1-2 |
Training Course, 1944 |
|
3 |
|
|
|
Series 1, Subseries 4: Ionosphere Station Reports, 1941-1946 |
|
|
Australia |
|
|
Christmas Island: Monthly Summaries, 1944-1945 |
|
4 |
Canada |
|
|
Clyde/Baffin Island: Monthly Summaries, 1943-1946 |
|
5 |
Iceland |
|
|
Reykjavik: Monthly Summaries, 1944-1945 |
|
6 |
Peru |
|
|
Huancayo: Monthly Summaries, 1944-1945 |
|
7 |
Trinidad |
|
|
Monthly Summaries, 1944-1945 |
|
8 |
Report: 1944-1946 |
|
9 |
United States |
|
|
College, Alaska |
|
|
Auroral Reports, 1942-1945 |
|
10-11 |
Bi-Monthly Progress Reports, Oct. 1941-Oct. 1942, Nov. 1942-May 1943 |
|
12-13 |
Direction-Finder Reports, 1942-1945 |
|
14-17 |
Ionospheric Results, 1941-1945 |
|
18-20 |
Miscellaneous Reports, 1941-1945 |
|
21-22 |
Monthly Reports to Director, 1941-1944 |
|
23 |
Monthly Summaries, 1943-1945 |
|
24 |
Signal Intensity Measurements, 1942-1945 |
|
25 |
Hawaii |
|
|
Monthly Summaries, 1944-1945 |
|
26 |
Combined Reports, 1946 |
4 |
5 |
|
|
|
Series 1, Subseries 5: Wave Propagation Committee files, 1942-1946 |
|
|
JX/WP Series |
|
|
Agendas, 1943-1946 |
4 |
6 |
Minutes of Meetings, 1942-1946 |
|
7-12 |
Notes by the Secretaries, 1942-1945 |
|
13-15 |
CX/WP Series |
|
|
Agendas, 1942-1946 |
|
16 |
Minutes of Meetings, 1942-1946 |
|
17-18 |
Minutes of Meetings, 1942-1946 |
5 |
1-3 |
Notes by the Secretaries, 1942-1945 |
|
4-10 |
CCB Series |
|
|
Notes by the Secretaries, 1942-1945 |
|
11-14 |
[CCB and JCB Series] Radiograms, 1942-1945 |
|
15 |
Roster of Membership Committees (as of March 1946) |
|
16 |
Memoranda for Information, 1942-1946 |
|
17 |
|
|
|
Series 1, Subseries 6: Miscellaneous files, 1936-1948, n.d. |
|
|
Berkner, L.V.: Publications and reprints, 1939-1948 |
5 |
18 |
Blueprints for Ionospheric Laboratory and Field Station, 1943 |
3 |
27 |
Cosmic Data [Report of Geomagnetic Activity], 1941-1946 |
|
28 |
Code Instruction, 1942 |
|
29 |
External Data: Canadian Radio Wave Propagation Committee, 1947 |
5 |
19 |
Films |
|
|
�First Motion Picture of the Ionosphere,� 1946 (2 films) |
14 |
|
�Motion pictures of the ionosphere,� 1946 |
|
|
�copy sound type film� [otherwise unlabeled], n.d. |
|
|
�First Motion Picture of the Ionosphere,� 1946 (2 films) |
|
|
�Kensington [MD], Moderate Storm Period, June 3-9, 1946� |
|
|
�November 17, 1948� |
|
|
[2 unlabeled films in small black film cans] |
|
|
[Ionosphere station in tropics; people conducting work at station, n.d.] (2 films) |
|
|
Memorandum re: Harvard University Eclipse Expedition to South Africa, 1940 |
3 |
30 |
Office of War Information: Broadcast Schedules, 1944-1945 |
6 |
1 |
Paper and Lecture: Automatic Multifrequency Technique for Ionospheric Measurements by Berkner, Wells, and Seaton, 1936 |
3 |
31 |
Photograph Album |
12 |
1-5 |
Photographs of HMO [Huancayo Magnetic Observatory] Installation for WMO [Watheroo Magnetic Observatory], n.d. |
|
32 |
Photograph: Radio Wave propagation Conference, 1945 |
|
33 |
Reprints: External, 1933, 1938-1949 |
6 |
2 |
Reports and Bulletins: External |
|
|
Canadian Radio Wave Propagation Committee, 1944-1946 |
6 |
3-4 |
National Research Council of Canada Radio Branch, 1942-1943 |
|
5 |
South African Council for Scientific and Industrial Research, 1946 |
|
6 |
Spitsbergen Report, ca. 1943 |
|
7 |
Technical Reports: CIW-- prepared under government contracts, 1942-1946 |
|
8 |
Technical Reports: External, 1943 |
|
9 |
|
|
|
Series 2: Data, 1933-1956 [bulk 1933-1946] |
|
|
Australia: Christmas Island |
|
|
Manual Equipment, Dec. 1944-Apr. 1945 |
10 |
1-5 |
|
|
|
Australia: Watheroo Magnetic Observatory |
7-8 |
|
Ionospheric Observatory Cahiers, 1933-1936 |
|
|
Ionospheric Log Sheets, 1933-1938 |
|
|
Atmospherics, 1935-1936 |
|
|
Battery Cahier, 1933-1938 |
|
|
Battery Log and Charging Log, 1939-1946 |
|
|
Battery Capacity Test, 1939-1942 |
|
|
DC Power Equipment Cahiers |
|
|
Machine Operation, 1936-1946 |
|
|
Maintenance Log, 1939-1944, 1945-1946 |
|
|
AC Power Equipment Cahiers |
|
|
Maintenance Log, 1938-1946 |
|
|
Running Log, 1938-1946 |
|
|
Ionosphere Equipment Cahiers |
|
|
Ionosphere Equipment, 1933-1938 |
|
|
Tube Log, 1938-1945 |
|
|
Running Log, 1938-1945 |
|
|
Maintenance Log, 1938-1945 |
|
|
Monthly Calibration Log, 1938-1946 |
|
|
Fade Out Summary, 1938-1946 |
|
|
Ionospheric Apparatus No. 2 and Power Equipment, April 1946-June 1947 |
|
|
Mean Hourly Values, 1941-1946 |
|
|
Ionosphere Building Control Data: Thermograms, 1937- |
|
|
Transmitted Messages, 1933-1938 |
|
|
Received Messages, 1935-1939 |
|
|
|
|
|
China: Wuchang |
8 |
|
Ionospheric Observations by C.T. Kwei at Central China College, 1937-1938 |
|
|
|
|
|
Peru: Huancayo Magnetic Observatory |
8-9 |
|
Ionospheric Cahiers (Observation), 1933-1935, May-Dec. 1946, Jan., Mar.-June 1947 |
|
|
Ionosphere Log-Sheets, 1934-1937 |
|
|
Seismological Cahier, 1932-1936, June 1947 |
|
|
Ionosphere Apparatus and Instructions, 1933-1938 |
|
|
Battery Cahier, 1933-1936 |
|
|
Battery Logs, 1939 |
|
|
Battery Capacity Test, 1939 |
|
|
DC Power Equipment Cahiers |
|
|
Power Operation, 1935-1946 |
|
|
Maintenance Log, 1939-1946 |
|
|
AC Power Equipment Cahiers |
|
|
Maintenance Log, 1939-1946 |
|
|
Running Log, 1939-1940 |
|
|
Ionosphere Equipment Cahiers |
|
|
Tube Log, 1938 |
|
|
Running Log, 1938-1946 |
|
|
Maintenance Log, 1945-1946 |
|
|
Monthly Calibration Check, 1938-1946 |
|
|
Fade Out Summary, 1939-1945 |
|
|
Field Intensity Maintenance Log, 1945-1946 |
|
|
Mean Hourly Values of Ionospheric Data, 1941-1944 |
|
|
Median Hourly Values, 1945-1946 |
|
|
Transmitted Messages, 1933, 1935, 1937-1938 |
|
|
Received Messages, 1936-1939 |
|
|
|
|
|
United States: College, Alaska |
|
|
Ionosphere Results, 1933- |
9 |
|
Weekly Ionosphere Disturbance Ratings, 1941-1942 |
|
|
Weekly Fade-out Summary, 1941-1943 |
|
|
Auroral Camera Log, 1943-1945 |
|
|
Direction Finder, 1944-1945 |
|
|
Signal Intensity Recorders Maintenance Log, 1941-1945 |
|
|
Zenith Weather, 1945 |
|
|
DC Power Equipment Cahier, 1941-1942 |
|
|
AC Power Equipment Cahier, 1941-1942 |
|
|
Ionospheric Equipment Cahiers |
|
|
Running Log, 1941-1946 |
|
|
Maintenance Log, 1941-1946 |
|
|
Monthly, 1941-1946 |
|
|
Fade-Out, 1941-1946 |
|
|
Mean Hourly Values, 1941-1945 |
|
|
Median Hourly Values and Fade-Out Summary, 1949-1950 |
|
|
Yearly Reposts, 1941-1945 |
|
|
Car Log, 1943-1944 |
|
|
Aurora Log, Dec. 1941-Feb. 1942 |
10 |
6 |
Aurora Notation, Dec. 1941-Feb. 1942 |
10 |
7 |
General Condition of Weather and Isolated Aurora, Oct. 1932-May 1933 and Visual Observation Aurora, 1932-1933 |
15 |
|
Auroral Record, 1942-1943 |
15 |
|
K-indices; Gamma Ranges; Visual Aurora, 1942-1946 |
15 |
|
A-1: Aurora [Tabulation of K and graphs], ca. 1945 |
15 |
|
A-2: Aurora Camera Films and Records, 1941-1942 |
15 |
|
Aurora Camera Films and Records, 1943 |
15 |
|
Maximum Usable Frequencies, 1941-1942 |
10 |
8 |
Report of SID in Signal Intensities, Aug.1941-March 1942 |
10 |
9-10 |
Reports, Diagrams, and Miscellaneous, n.d. |
6 |
10 |
Traces, Sept.-Dec. 1933, Jan.-May 1934 |
6 |
11-12 |
Weekly Field Intensity Data, Aug.-Oct. 1941, Dec. 1941, Jan.-Feb. 1942 |
10 |
11-13 |
Weekly Ionosphere Data, Aug.-Dec. 1941, Jan. 1942 |
10 |
14-15 |
Ionosphere Data, 1954-1956 |
13 |
|
|
|
|
United States: Washington, DC |
|
|
Ionospheric Observations from URSI Data, 1933-1936 |
9 |
|
|
|
|
Series 3: Research Notebooks, 1927-1950s |
|
|
Direction Finding Reflection: O.D. [Odd Dahl], 1927-1928 |
11 |
1 |
Heaviside Layer Oscillograms, 1925-1930 |
|
2 |
Heaviside: P.G. [Potential Gradient], 1926-1927 |
|
3 |
Radio Echoes: Bellevue [Naval Research laboratory site, Washington, D.C.], 1929 |
|
4 |
Items from Radio Echoes: Bellevue [Naval Research laboratory site, Washington, D.C.], 1929 |
|
5 |
Radio Echoes, 1929-1930 |
|
6 |
H.W. Wells: Personal, 1938-1946 |
|
7 |
H.W. Wells, 1950s |
|
8 |
Subject Terms
Topics:
Auroras
Ionosphere
Radio wave propagation
World War, 1939-1945
Corporate Names:
Carnegie Institution of Washington. Dept. of Terrestrial Magnetism
Central Radio Propagation Laboratory (U.S.)
Interservice Radio Propagation Laboratory (U.S.)
United States. Federal Communications Commission
United States. Joint Communications Board
United States. National Bureau of Standards
Personal Names:
Berkner, Lloyd V. (Lloyd Viel), 1905-
Breit, Gregory, 1899-
Dahl, Odd, 1898-1994
Tuve, Merle Antony, 1901-1982
Wells, Harry Warren, 1907-
Forms:
Agendas (administrative records)
Blueprints
Correspondence
Laboratory notebooks
Minutes
Logs (records)
Photographs
Photograph albums
Bibliography
Brown, Louis. Centennial History of the Carnegie Institution of Washington. The Department of Terrestrial Magnetism. Cambridge: Cambridge University Press, 2004.
�The Ionosphere and Its Relations to Geomagnetism Summary of War Activities, 1942-1946�. Carnegie Institution of Washington Year Book, v. 45, (pp. 54-56). Washington, DC: Carnegie Institution of Washington., 1946.
Related Collections
Instrument and Equipment Records, 1892-1970, Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington, D.C.
Drawings and plans for buildings at the ionospheric stations are located in the DTM Archives.