Warner's diaries provide an intimate record of his far-flung travels. Alongside visits to zoological and mineralogical collections, Warner patronizes numerous places of worship, for which he often provides sketches of murals and architectural features. (His most impressive color illustrations begin around March 1863). Notably, he visits a Jewish synagogue in the Netherlands (10/13/1862) and a mosque in the Middle East (3/31/1865). He copies verses from a tombstone (9/8/1862), and when he tours the Egyptian pyramids, he records hieroglyphics (4/26/1865). He encloses descriptions of natural scenes—e.g. the Wetterhorn (8/31/1862) and Rhone Glacier (9/4/1862)—and also urban spaces, including a locomotive works in Amsterdam (1/26/1863), a foundry in Greenock (1/30/1863), a prison in York (4/7/1863), a gypsy settlement in Romania (6/13/1865), and even an early account of the Grand Kremlin Palace (8/2/1868).
 
Throughout those travels, Warner recollects his native Pennsylvania to draw evocative geographic and social comparisons. For example, he equates a town outside Belgrade to Burlington on the Delaware (6/9/1865). Upon meeting a foreman at machine shop, he compares the conditions of the poor in America and Germany (8/25/1862). Of particular note, he compares the governor of Nazareth to a "Philadelphia negro" (4/15/1865).
 
At various points in his travels, Warner is compelled to confront U.S. domestic affairs, most especially the Civil War. For example, traveling by rail in Germany in late-1865, he writes, "Met in the [train] car Mr. Joseph Kommer, Lincoln Logan Co., Illinois, a few months back to Germany, now on his way home via Hamburg. He had served in the Northern Army
 
related many things respecting the war and was a good union man" (11/8/1865). Several years later, he visits a castle where he notes a "revolver presented to the King by President Lincoln" (7/9/1868). Although Warner rarely discusses politics directly, he registers his own political activities and sympathies. For example, he attends a "Peace Society" (5/19/1863), a "temperance tea" (9/15/1863), and a lecture on "dwellings for workingmen" (1/6/1866). He records at least one conversation about U.S. nativist movements, particularly the Astor Place Riots, writing, "Met an Irishman who had been in the U.S. some years ago. He doubted whether the Irish, in New York had been incited—as a clan, especially—to take part in the late New York riots, and on account of jealousy of the blacks as competitors for work—he was further opposed to Mr. Lincoln's emancipation edict" (8/18/1863). In another prescient entry, he records an exchange with a Polish miller about poll taxes. "A miller spoke to me, among other subjects, of Poland," Warner writes. "He said Austria and Prussia assist to subjugate Poland, because 'they are all tyrants together.' Of our country, he said there would soon be poll tax" (9/14/1864).
 
When it comes to the topic of slavery, Warner reveals abolitionist sympathies via ephemera. He encloses a newspaper clipping from "Aborigine Protection Society," after which he remarks on the emigration of freed slaves to Liberia (5/20/1863), and encloses another clipping entitled "Negro Emancipation" (6/17/1863).
 
Scholars of nineteenth century material culture will be richly rewarded by the diaries. Alongside hand-drawn maps of buildings, cities, and architectural features, Warner encloses numerous newspaper clippings (e.g. (1/10/1863), engravings (9/27/1864), advertisements (7/9/1865), and theatrical programs (10/6/1865). While the majority of those materials are in English, some ephemera—and Warner's own entries—are in German, French, or Italian.

With 55 volumes spanning 7/8/1862-11/23/1872, the John Warner diaries provide a detailed account of his time abroad (1862-1868) and travels throughout Europe. Although many entries are devoted to talks and lectures (mostly pertaining to zoology), Warner proves also a studious observer of people, cultures, and cultural and religious institutions, which he records through numerous sketches and ephemera. In fact, these volumes present a wealth of research opportunities for scholars of material culture, thanks to Warner's curation of nineteenth-century newspaper clippings, advertisements, programs, and personal illustrations.
 
Warner's diaries provide an intimate record of his far-flung travels. Alongside visits to zoological and mineralogical collections, Warner patronizes numerous places of worship, for which he often provides sketches of murals and architectural features. (His most impressive color illustrations begin around March 1863). Notably, he visits a Jewish synagogue in the Netherlands (10/13/1862) and a mosque in the Middle East (3/31/1865). He copies verses from a tombstone (9/8/1862), and when he tours the Egyptian pyramids, he records hieroglyphics (4/26/1865). He encloses descriptions of natural scenes—e.g. the Wetterhorn (8/31/1862) and Rhone Glacier (9/4/1862)—and also urban spaces, including a locomotive works in Amsterdam (1/26/1863), a foundry in Greenock (1/30/1863), a prison in York (4/7/1863), a gypsy settlement in Romania (6/13/1865), and even an early account of the Grand Kremlin Palace (8/2/1868).
 
Throughout those travels, Warner recollects his native Pennsylvania to draw evocative geographic and social comparisons. For example, he equates a town outside Belgrade to Burlington on the Delaware (6/9/1865). Upon meeting a foreman at machine shop, he compares the conditions of the poor in America and Germany (8/25/1862). Of particular note, he compares the governor of Nazareth to a "Philadelphia negro" (4/15/1865).
 
At various points in his travels, Warner is compelled to confront U.S. domestic affairs, most especially the Civil War. For example, traveling by rail in Germany in late-1865, he writes, "Met in the [train] car Mr. Joseph Kommer, Lincoln Logan Co., Illinois, a few months back to Germany, now on his way home via Hamburg. He had served in the Northern Army
 
related many things respecting the war and was a good union man" (11/8/1865). Several years later, he visits a castle where he notes a "revolver presented to the King by President Lincoln" (7/9/1868). Although Warner rarely discusses politics directly, he registers his own political activities and sympathies. For example, he attends a "Peace Society" (5/19/1863), a "temperance tea" (9/15/1863), and a lecture on "dwellings for workingmen" (1/6/1866). He records at least one conversation about U.S. nativist movements, particularly the Astor Place Riots, writing, "Met an Irishman who had been in the U.S. some years ago. He doubted whether the Irish, in New York had been incited—as a clan, especially—to take part in the late New York riots, and on account of jealousy of the blacks as competitors for work—he was further opposed to Mr. Lincoln's emancipation edict" (8/18/1863). In another prescient entry, he records an exchange with a Polish miller about poll taxes. "A miller spoke to me, among other subjects, of Poland," Warner writes. "He said Austria and Prussia assist to subjugate Poland, because 'they are all tyrants together.' Of our country, he said there would soon be poll tax" (9/14/1864).
 
When it comes to the topic of slavery, Warner reveals abolitionist sympathies via ephemera. He encloses a newspaper clipping from "Aborigine Protection Society," after which he remarks on the emigration of freed slaves to Liberia (5/20/1863), and encloses another clipping entitled "Negro Emancipation" (6/17/1863).
 
Scholars of nineteenth century material culture will be richly rewarded by the diaries. Alongside hand-drawn maps of buildings, cities, and architectural features, Warner encloses numerous newspaper clippings (e.g. (1/10/1863), engravings (9/27/1864), advertisements (7/9/1865), and theatrical programs (10/6/1865). While the majority of those materials are in English, some ephemera—and Warner's own entries—are in German, French, or Italian.