For over a century and a half, historians have counted themselves fortunate that Professor Michael Jacobs took detailed weather observations  during the Battle of Gettysburg.  His  reasons for doing so, however, remained a mystery.  Why did he do it?  Did he conduct weather observations as a  matter of routine?  Was it a hobby?  Certainly, it could be said that as a professor of mathematics and physical science he maintained a keen interest in  the weather.  But in actuality there is  more to it than that.  Regarding his  observations, the equally perplexing question of what happened to his original  records has puzzled historians for years.   Interestingly, the oft quoted primary source of weather conditions during the battle is an article entitled Meteorology of the Battle, that  comes to us through the professor’s son 22 years after the battle.  Although this article is based on Professor Jacobs’s original observations, the source’s documents seemed to have been lost  to the ages.  Fortunately,  this is not the case.  Indeed, the  questions of why Professor Jacobs recorded such detailed weather observations during the battle and what happened to his original records can  now be answered.¹  

In many ways the Rev. Dr. “Professor” Michael Jacobs could be considered a “Renaissance Man.”  Born in  Franklin County, Pennsylvania in 1808, Jacobs attended Jefferson College (now Washington and Jefferson College).   Jacobs came to Gettysburg in 1828 to assist his brother David with the newly founded school known as the Gettysburg Gymnasium.  By 1832 the  school received its state charter as a college and Michael Jacobs found himself  one of the founding instructors at what was  known then as Pennsylvania College (later Gettysburg College).  Jacobs first served as an instructor in Mathematics, Chemistry and Natural Philosophy (physical science). By 1841 he was also teaching meteorology.² It is worth noting here that his lessons in  meteorology were reportedly the second such college-based program known to exist in the United States.³  

But Professor Jacobs was perhaps best known, at least during his  lifetime, for writing one of the first published histories of the battle –  Notes on the Rebel Invasion of Maryland and Pennsylvania and the Battle of Gettysburg, July 1st, 2nd and 3rd, 1863. This  book became so well-known that requests for copies came from far and wide to  include not only ordinary citizens but prominent veterans of the battle as  well.⁴  The book was so wildly popular that Jacobs even felt compelled to send a copy to President Abraham Lincoln.⁵

In reading about Professor Jacobs’s interest in nature and  meteorology, as conveyed to us by former students and contemporaries alike, one  can readily see how he kept a fervent interest in the weather.  Though he was quite astute in classroom  lecture, primary sources indicate that Professor Jacobs’s true strong-suit as a  teacher rested in lessons held outside the classroom.  Known for regularly leading learning sessions  during which students tramped the terra firma surrounding both the campus and  the town, Jacobs left a lasting impression on his students and earned the  admiration of his family and colleagues.⁶  These lessons covered matters of science and nature to include the weather, flowers and fauna of the area; all subjects in which it seems he was  thoroughly interested.

Professor Jacobs was also instrumental in establishing Gettysburg  Gasworks, the company that first gave Gettysburg light on its public streets.⁷  All of these efforts took place against the backdrop of religion as Jacobs  was a self-taught theologian and was licensed as a Lutheran Minister.  For a time, he served as clergyman of  Gettysburg’s Christ Lutheran Church. Though health issues forced him  to retire in 1866, he remained a professor emeritus until his death in 1871.⁸  

Few, if any, Civil War historians of the battle have likely  studied the contributions to weather forecasting made by two notable  meteorologists, James Espy and Joseph Henry, at least not with regard to how  their careers related to the battle.  It  is through their efforts that we have come to know Professor Jacobs as a  weather observer. Thanks to two wonderful books: the Philadelphia Area Weather Book  and the  Pennsylvania Weather Book, the author learned how the careers of Espy and Henry were interwoven with that of Jacobs.⁹   

As it happens, during the mid-1830s, early weather forecasting pioneer James Espy, of Philadelphia’s Franklin Institute, sought to establish a statewide weather observer network in Pennsylvania.¹⁰  Under this program, Jacobs served as the Adams County observer.  Thus, beginning in April of 1840, Professor Jacobs began thrice daily weather observations, made at 7a.m., 2p.m., and 9p.m., keeping a record of these observations in a journal expressly dedicated to this purpose.¹¹ Jacobs’s weather observations included not only temperature readings, but cloud formation notations, wind speeds, precipitation measurements, and  barometric pressure readings.¹²  

By 1842 Espy had accepted a Congressional appointment as  Meteorologist to the U.S. War Department.  He later moved to a similar position with the U.S. Navy.¹³  Subsequently, he worked under the auspices of the Smithsonian Institution.¹⁴  Meanwhile, his Pennsylvania-based  weather observance program had shed light on the potential benefits of nationwide weather observations. The results of Espy’s work quickly drew the attention of the Smithsonian  Institution’s first Secretary, Joseph Henry.  A notable scientist and meteorologist in his own right, Henry would  eventually come to be known as the “Father of Weather Forecasting.”¹⁵  A crucial step in earning this moniker were his efforts to build upon the successes of Espy’s program through the establishment the country’s first nationwide weather observer network. 

Working with Espy, Henry established the first nationwide network of weather observers in 1849.¹⁶  Known as the “Smithsonian Metrological  Project” the program included 150 observers.¹⁷ Once again, Professor  Jacobs served as the observer for Adams County.  From this point forward, Jacobs recorded his observations on a special form provided to him by the Smithsonian.¹⁸  Professor Jacobs continued his weather observations on behalf of the Smithsonian through February of 1865.¹⁹  

Of course, most of Professor Jacobs’s nearly three decades of  recording weather observations took place under far less trying circumstances  than those he made during the battle.  Jacobs’s diligence during the battle is remarkable, especially considering that the Confederate army’s line of battle literally rested on his  doorstep for a large share of the battle.²⁰   Indeed, much like a 19th  century version of the brave meteorologists from The Weather Channel known for their fearless field reporting during dangerous storms, Jacobs was  not kept from making his weather observations by the “storm” swirling around him.  But this “storm” was no hurricane, nor was it a blizzard.  Rather, this “storm” was the largest battle to ever take place in the Western Hemisphere.²¹  

In any event, from 1849 forward, Espy and Henry continued to forge ahead in their efforts to develop a method of weather forecasting through the use, and subsequent analysis of, the information gleaned by observers and a  smaller network of weather observation telegraph relay stations.   Espy retired in 1857 and died in 1860, before realizing his dreams of a national weather service.²²  Though Henry’s continuing efforts were  derailed somewhat by the Civil War, he forged ahead.  Ultimately, the fruits of his and Espy’s  labors led Henry to suggest and lobby for the establishment of a federally operated national weather service.²³  With the able assistance of a few key individuals, his suggestion came to fruition on February 9, 1870 when a joint Congressional resolution signed by President Ulysses S. Grant authorized a national weather bureau.²⁴  The responsibility for meeting the requirements of the resolution went to the  U.S. Signal Corps under Brigadier General Albert J. Meyer.²⁵  Fittingly, Professor Jacobs’s classroom lessons on Meteorology  served as a template for training government weather forecasters under the U.S. Signal Corps as part of the development of the National Weather Service.²⁶   

We can now understand why Professor Jacobs conducted detailed weather observations.  We also see how  his interest in meteorology and his efforts as a weather observer played an  important role in the development of the National Weather Service.  But this is only half of the research  equation.

Having determined why Professor Jacobs recorded weather observations, the question begged, what happened to his original observation  records?  Learning that his efforts were  on behalf of the Franklin Institute and the Smithsonian Institution proved  crucial to the search.  But this knowledge came after the initial effort to locate Jacobs’s records.

Prior to understanding Professor Jacobs’s role as a weather observer, the quest to locate his weather observation records for July of 1863  had focused on what seemed to be logical repositories for such records.  This included Gettysburg College’s Musselman  Library Special Collections and Archives, the Lutheran Theological Seminary Archives  (in both Gettysburg and Philadelphia), the Adams County Historical Society, and Gettysburg National Military Park’s Library and Archives.

Though most of these efforts proved fruitless in terms of locating Professor Jacobs’s original daily observation records, research at Musselman  offered an important clue in the form of select portions of Professor Jacobs’s  annual weather observation summaries.²⁷  As it happens, these records had been obtained by Musselman from the National Oceanic and Atmospheric Administration’s (NOAA)  National Centers for Environmental Information (NCEI).²⁸  Although the NCEI records held by the library archives did not include  Professor Jacobs’s daily weather observation, it appeared as though the NCEI might be a source for further investigation.

Adding to this, concurrent research unsurfaced an article entitled The Weather at Gettysburg, published in 1960 by eminent meteorologist and weather historian, the late David M. Ludlum.²⁹  Interestingly, the article clearly indicated that the NCEI, at least as  of 1960, held copies of Professor Jacobs’s original daily weather observation records.³⁰  However, in the same breath, Ludlum’s article indicated that he  believed the original records had been destroyed once the records had been microfilmed, in 1940.³¹  Regardless, one was left to wonder if the NCEI still maintained copies  of Professor Jacobs’s original records. In addition, a subsequent conversation with a colleague who had conducted weather-oriented research as it related to the restoration of the famous Gettysburg Cyclorama further indicated that contacting the NCEI might  offer some degree of promise.³² 

This knowledge, coupled with  subsequent enlightenment as to Professor Jacobs’s role as a weather observer, proved to be the turning point in locating his records. Focusing on Jacobs’s efforts on behalf of the  Franklin Institute, an earnest Internet search uncovered a promising collection  of weather-related data at the American Philosophical Society (APS – located in  Philadelphia, Pennsylvania).³³  

Parallel efforts with the Smithsonian Institution offered some hope as well. Subsequent research revealed not only that the Smithsonian’s holdings held promise but that those of the National Archives did as well.  Unfortunately, further research at the  Smithsonian indicated that, though their holdings included some meaningful  documentation relating to Professor Jacobs’s weather observation activities, they held no copies of his daily observations. However, research at the National Archives proved otherwise with regard to their holdings.³⁴ 

Continued research based on the aforementioned leads soon  confirmed what had been the author’s wildest dream – the APS confirmed that their “Meteorological Observations Made for the Franklin Institute 1839-1865” collection included an original set of Professor Jacobs’s original daily weather observation records, both those made for the Franklin Institute and  those made on behalf of the Smithsonian Institution.³⁵  In essence, this collection was the “Holy  Grail” of Jacobs’s weather observation records. In addition, research confirmed that both the NCEI and the National  Archives held microfilm copies of almost all of Professor Jacobs’s daily observation records obtained on behalf of the Smithsonian Institution.³⁶  In many cases, holdings among all three archives included peripheral documentation pertaining to Professor Jacobs’s observations of other weather-related matters such as area auroras, flowers, and fauna.³⁷  

Moreover, further research determined a very interesting twist. It seems that Professor Jacobs wisely created  two sets of original daily observation records.³⁸  One set he submitted to the Smithsonian, on a monthly basis, while  keeping the other set as a back-up copy. As it turns out, the originals from which the NCEI and the National  Archives derived their microfilm copies were destroyed (post-microfilming) as  suspected by Ludlum.  However, it appears  the second set of originals kept by Jacobs passed from him to the Lutheran Seminary Archives (perhaps via his son) and ultimately to the APS  Archives.  When comparing the daily  weather observation forms for July of 1863 (NCEI/NA copies vs. APS originals), one can readily see that the same information is presented save for certain highlighted items.  For example, the professor circled the high and low temperatures for the month on the copy he submitted to the Smithsonian, while he did not do so on the copy he retained.

This new knowledge is crucial for many reasons but perhaps no more than the fact that the NCEI and the National Archives records are missing the  monthly reports for August – December of 1863 and January – June of 1864.  All of the records for these months, save for August 1863, can be found in the APS collection.  Thus, the APS holdings offer historians key weather data relating to the days leading up to the Battle of Gettysburg, the aftermath of the battle, the weather during President Lincoln’s Gettysburg  Address (Nov 1863), and more; data that is missing from the NCEI and National  Archives collections.³⁹  As such, the APS holdings greatly amplify and indeed expand upon the  limited information available from Meteorology of the Battle while also filling key voids in the NCEI and NA holdings.

Thus, the question, Why did Professor Jacobs record such detailed weather observations during the battle – can now be put to rest.  As detailed above, his steadfast  efforts in this regard can be viewed against the backdrop of knowing that the weather observations he made during the battle were actually part of an effort  that lasted at least 26 years.  Ultimately, Jacobs’s efforts contributed to the establishment of the  National Weather Service. 

The question: What happened to Professor Jacobs’s original records – can also be answered.  It is satisfying for historians to know that  Professor Jacobs’s weather observation records, once thought to either be lost  or scattered to the four winds, are safely secured for posterity in three places, with one of those repositories (APS) holding an original set.

With this, Professor Jacobs’s original weather observation records, for the entire Gettysburg Campaign, stand ready for further study by historians.  Coupled with the plethora of  battle-related information that has emerged in the nearly 60 years since  Ludlum’s landmark analysis of weather’s impact on the battle, Civil War historians may now gain new insights with regard to the weather’s impact on the entire Gettysburg Campaign and its aftermath. In addition, Jacobs’s 26 years of  detailed weather and weather-related observations (flowers, fauna, etc.) may prove invaluable to environmental historians. 

When David Ludlum penned his article The Weather at Gettysburg,  he opened it with the simple quote once inked by Professor Jacobs on the  momentous occasion of filing his July 1863 weather observation report:    “Great  battles of Gettysburg fought.”  Seeing those words on a copy of the original  source document represents a spine-tingling moment that will never be  forgotten.  It is what keeps this author "on the path of history."⁴⁰

Sources:  Archives:  American  Philosophical Society. Library Archives. Meteorological observations made for  the Franklin Institute 1839-1865, Mss 551.5.j12.  Gettysburg College, Musselman Library Archives.  Michael Jacobs Collection, MS-107, and VFM 386.   National Archives. RG 27, Microfilm Publication T907, Reel 445.  National Oceanic and Atmospheric  Administration (NOAA), National Center for Environmental Information (NCEI),  Asheville, NC.  Monthly weather records  from U.S. Army Forts stations (1820-1871), U.S. Army Signal Service Stations  (1871-1892), Smithsonian Institution’s voluntary observer network (1848-1875),  and other stations which conducted weather observations in the 19th  century (FORTS) Database.  Smithsonian  Institution.  Record Unit 60:  Smithsonian Institution Meteorological  Project, Records 1849-1875, and related records from 1820.  Record Unit 52, Box 16, Folder 17.   Books : Breidenbaugh, E. S.  The  Pennsylvania College Book, 1832-1882 . Philadelphia, PA:  Lutheran Publication Society, 1882.  (Biographical sketch of Professor Michael Jacobs, D.D. by Professor C.A. Hay  D.D.)  Gebler, Ben.  The  Pennsylvania Weather Book . New Brunswick, NJ:  Rutgers University Press, 2002.  Hefelbower, Samuel Gring.  The  History of Gettysburg College, 1832-1932 .   Gettysburg, PA:  Gettysburg  College, 1932.  Jacobs, Henry  Eyster.  Lincoln’s  Gettysburg World-Message .   Philadelphia, PA:  United Lutheran  Publication House, 1919.  Jacobs, Henry Eyster.  Memoirs  of Henry Eyster Jacobs .  Vols. 1-3: Notes on a Life of a Churchman .  Huntington, PA: Church Management Service,  Inc. 1974 (Written in 1906.  Edited by  Henry Eyster Horn in 1938).  Jacobs,  Michael.  Notes  on the Rebel Invasion of Maryland and Pennsylvania and the Battle of  Gettysburg, July 1st, 2nd and 3rd, 1863 .  Philadelphia:  J.B. Lippincott,  1864.  Nese, Jon and Glenn “Hurricane”  Schwartz.  The  Philadelphia Area Weather Book .   Philadelphia, PA:  Temple  University Press, 2002.   Magazine and Newspaper Articles :  Boardman, Sue and Elle Lamboy.  “An Historic Weather Report.”  Celebrate Gettysburg Volume 12 (Sep/Oct  2017), Issue 64, p. 16.  Gettysburg  Compiler, “The Gas Works Finished – A Complete Success,” and “Lighting The  Streets,” August 20, 1860  Gettysburg  Star & Sentinel, “Gaslight! Gaslight!” October 31, 1859.  Gettysburg Star & Sentinel, Jacobs, Henry  Eyster.  “Meteorology of the Battle,”  August 11, 1885.  Ludlum, David M. “The  Weather at Gettysburg.”  Weatherwise,  June 1960.   Museum and Wayside Displays :  Seminary Ridge Museum Display “Dr. Henry  Eyster Jacobs”.  The Michael Jacobs  House, Main Street Gettysburg, “What in your life you will never see again.”   Websites :  Amphilsoc.org.  Britannica.com, James Espy biographical  sketch.  Gettysburg.edu (Gettysburg  College), “Portrait of Michael Jacobs, Michael Jacobs Collection  Biography.  Also “Michael Jacobs:  Innovative Curiosity” (Script for  Interpretive Tour Program, J. Rudy, HIST 418).   Historycentral.com, James Espy biographical sketch.  Library of Congress loc.gov, Abraham Lincoln  papers, Series 1. General Correspondence 1833-1916: Michael Jacobs to Abraham  Lincoln, Saturday October 24, 1863 (Send book on Gettysburg).  Smithsonian Website ssec.di.edu, article  “Joseph Henry:  The Father of Weather  Forecasting (And the First Smithsonian Secretary).  Excerpt from the Weather and Climate Systems  Unit of Smithsonian Institute curriculum product line, STCMS, published by Carolina  Biological.  Weather.gov, History of the  National Weather Service.  Wikipedia.org,  James Espy biographical sketch.

Footnotes: 

1. Gettysburg Star & Sentinel, Aug. 11, 1885, p. 1. 

2.  Ludlum, p. 105.  Hefelbower, p. 109.  Gettysburg.edu. Bio sketch of Professor  Jacobs. 

3.  Ibid.,p. 130. 

4.  Michael  Jacobs Collection, Gettysburg College. Folder MS-107, Memoirs of H.E. Jacobs (hereafter  “Memoirs”), p. 63. 

5.  Michael  Jacobs Collection, Gettysburg College, Folder MS-107.  Library of Congress (loc.gov).  Abraham Lincoln Papers, Series 1. Michael  Jacobs to Abraham Lincoln, Oct. 24, 1863.   

6.  Hefelbower,  pp. 135-137.  Breidenbaugh, p. 160.  “Memoirs”, pp. 12-13. 

7. “Memoirs”, pp. 6-7.   Gettysburg.edu, “Innovative Curiosity”. 

8.  Ludlum, p. 105.  Gettysburg.edu, “Portrait of Michael Jacobs”. 

9.  Gelber, pp. 22-25.  Nese & Schwartz, pp. 6-11. “Memoirs”,  p. 12. 

10.  Ludlum, p. 101.  Gelber,pp. 22-25.  Nese & Schwartz, pp. 6-11. 

11.  Ibid. 

12.  Ibid. 

13.  Espy was  the first person assigned as Meteorologist for the U.S. Government.  Nese & Schwartz, p. 9. 

14.   Historycentral.com, Britannica.com.  Nese & Schwartz, pp. 6-11. 

15.  “Joseph Henry: Father of Weather Forecasting”, Smithsonian website ssec.di.edu. 

16.  Gelber, p. 24.  Nese & Schwartz, pp. 9-10. 

17.  Ibid.,p. 10. 

18. “Joseph Henry: The Father of Weather Forecasting”,  ssec.di.edu. 

19.  NOAA FORTS  Report, Feb. 1865.  Evidence suggests  that the Gettysburg weather station was unoccupied from March 1865 to July  1889. Musselman Library Archives  VFM-386. 

20.  Notes on  Rebel Invasion, pp. 24-25.  “Memoirs”, pp. 56-57.   

21.  Nese &  Schwartz, pp. 8-9. 

22.  Ibid., p.  11. 

23.  Ibid. 

24.  “Joseph Henry: The Father of Weather Forecasting”,  ssec.di.edu.  Nese & Schwartz, pp.  10-11. 

25.  Ibid. 

26.  Ludlum, p. 105. 

27.  Musselman  Library Archives, VFM-386. 

28.  Ibid. 

29.  Ludlum, pp. 101-105, 130.  Nese & Schwartz, p. 13. 

30.  Ludlum, p. 102. 

31.  Ibid. 

32.  The author  would like to acknowledge Ms. Karen Drickhamer and Ms. Catherine Perry of the Musselman  Library Archives and Special Collections.   Many thanks to Sue Boardman for research assistance. 

33. “Meteorological Observations Made for the Franklin  Institute, 1839-1865, Mss551.5.j12”, amphilsoc.org. 

34.  Smithsonian  Institution Meteorological Project, Records 1849-1875, and related records from 1820.  Record Unit 52, Box 16, Folder  17. 

35.  Meteorological Observations Made for the Franklin Institute, 1839-1875,  Mss551.5.j12. 

36.  NCEI’s FORTS database, National Archives, RG 27, Microfilm T907, Reel 445. 

37. “Memoirs”, p. 12. 

38.  Meteorological Observations Made for the Franklin Institute, 1839-1875,  Mss 551.5.j12.  Record Unit 52, Box 16,  Folder 17. 

39.  Ibid. Unfortunately, records of Aug. 1863 are missing. 

40.  Ludlum, p.  101.

Writer and historian Jeff Harding  is a licensed battlefield guide at Gettysburg National Military Park.  He also wishes to thank John Heiser at Gettysburg National Military Park Library and Tim Smith  of the Adams County Historical Society for their aid in his research for this  article. He is the author of the new book Gettysburg’s Lost Love Story.

This article originally appeared in the July 2018 issue of the Gettysburg Experience Magazine.