The short stay in Chile as a young man had heightened Augustus' appetite for a chance to spend more time in South America.  By the early 1860s, he had enough money from Calif-ornia land purchases to head south again.  This time he went to Peru perhaps drawn by stories, heard during his travels, of ruined ancient cities.  To support himself he set up a photo-graphic studio.

A short article published in Lima's El Comercio on March 27, 1862 announced the opening of the photographic studio of Los Senores Augusto Le Plongeon y Ca., Galeria Fotographica Norte Americana, modeled after American studios.  The studio had a special translucent glass light source for proper portrait lighting, as well as equipment from the U.S., England, and Germany.  It offered a special changing room for the ladies, and it promised prompt service.  Augustus listed 11 years of photographic experience and offered the choice of paper photography, daguerreotypes, or ambrotypes.

In addition to running the portrait studio, Augustus spent much of his time in 1862 and 1863 exploring and photo-graphing a number of archaeological sites in Peru.   Eventually he felt confident in his ability to create good photographic images on-site without a permanent dark-room.  He experimented with the new glass plate negative process, trying to perfect the techniques he had developed in St. Thomas.

The process was difficult enough under controlled studio conditions; in a remote Peruvian site it required creativity, patience, and much trial and error.  First Le Plongeon would coat the glass-plate with a wet collodion syrup made by dissolving cellulose nitrate, or gun cotton, in a solution of alcohol and ether.  He experimented with several formulas of iodide and bromide to be added to the collodion.  Then he would sensitize the plate by immers-ing it in a bath of silver nitrate.  After the plate was withdrawn from the bath, there was no time to waste.  It had to be mounted in the camera and exposed, then returned to the darkroom to be developed as quickly as possible.  Once prepared, the plate would steadily lose its sensitivity as the ether and alcohol slowly evapor-ated.

In July 1863 he agreed to assist Ephraim G. Squier, known for his earlier reports on archaeology in the Mississippi valley, in exploring and photographing the ruins.  He introduced Squier to a number of his friends who owned land on which ruins were located, accompanied him on several expeditions, and assisted him in various other ways.

When Squier left for New York, Le Plongeon entrusted in him a set of glass negatives to hand carry to a publisher, Anthony and Company.  Unbeknownst to Augustus, the material never reached the publisher.  Squier apparently kept the negatives to use in his own publications without crediting his collaborator.  Le Plongeon would not learn about this upsetting situation for almost a decade.  By then, it would be too late to do anything.

After he had been in Peru for a time, Augustus, a Freemason, felt compelled to speak out against what he thought were abuses by Jesuit priests and the Catholic Church, and wrote two books about religion and the Jesuits in Peru.  The first book, La Religion de Jesus Comparada con las Ensenanzas de la Iglesia, was published in 1867.  The second, Los Jesuitas e el Peru, appeared in 1869.

At about the same time, Augustus established a private medical clinic in Lima where he used the application of electricity in medicinal baths to promote healing of broken bones.  Augustus referred to it as "my electro-hydopathic establishment" (1878a).

This interest in electromagnetism may have led Augustus to what became an exhaustive study of earthquakes.  He followed one of the accepted scientific thoughts of the day which was based on electromagnetic theory, rather than on an under-standing of plate tectonics.  He found Peru to be the perfect natural laboratory for studying earthquakes and theorizing on their causes and effects.   Le Plongeon theorized that electromagnetic currents, in conjunction with chemical reactions, caused certain areas under the earth's crust to heat up.  Those locations, in turn, would superheat water until it became steam.  The resulting tremendous increase in pressure would move the steam through underground channels at high speed, thus disrupting the surface.

Magnetism, wrote Le Plongeon, "is, therefore, the life-sustainer, the soul, of the whole creation, of which our reduced planet is but one of the smallest atoms" (1872:541).  These concepts would also apply to living things, he reasoned, and thus could be used for healing purposes.  He attempted to do just that in applying galvanic currents to earthquake victims whose injuries he understood to be caused by the destructive effect of electromagnetic energy.

A major source of Le Plongeon's data was a devastating earthquake that hit Peru on August 13, 1868.  He observed the event and its aftermath and carefully recorded what he saw.  Noting the time of the tremor as exactly 4:46 p.m., he described the oscillatory motion of the repeated shocks and the tidal waves that followed.  "The shocks came from the south; the skies were stormy, a very light wind blew from a southerly direction.  The whole soil of the country, as far as it could be seen, was moving; first like a wave, from north to south, then it trembled, and at last upheaved heavily."  He traveled about the devastated country, inter-viewing victims and recording in detail the damage to many cities.  Some were totally destroyed by tidal waves; others were flattened by seismic waves.  He also wrote observations of animal premonitions occurring before a quake, a summary of seismic activity in Peru since the Conquest, and information on the effects of the August 13 tidal wave throughout the Pacific.

During his eight years in Peru, Augustus explored many sites on his own, including Tiahuanaco and other Prehispanic sites.  There was little known at the time about these monumental stone cities, some a thousand years old.  Augustus' inclination to jump into the unknown and find an explanation or a solution led him to study and scrutinize the ancient ruins looking for answers about their builders.  He began forming ideas on the origin of world civilization.  Until that time few theorists looked to the New World for origins, and considered it to be, if anything, inferior to the Old World.  Contrary to the more commonly held theories, Le Plongeon came to believe that the cradle of world civil-ization was in the New World.

He was familiar with the writings of the French scholar Brasseur de Bourbourg, whose history of New World civiliza-tions hypothesized that all civilization originated in the New World.  There was also Stephens and Catherwood's des-criptions of the magnificent ruins in Yucatan and Central America seen on their travels in the 1840s.  As Le Plongeon's knowledge developed, it became apparent to him that ancient civilizations in Mexico should be investigated.  Perhaps the ancient Maya cities held the answers to his questions.

Augustus felt compelled to share the information he had amassed in Peru with the scholars he knew back in California.  They would surely be as excited as he was about the natural phenomena and the exotic civilizations he had been observing.   In 1870 Le Plongeon returned by boat to San Francisco, where he made several appearances before the California Academy of Sciences.  On August l5 he lectured on some "remark-able" Peruvian skulls.  On September 5 he read part of a long article on "the aboriginal ruins of Peru" and ex-hibited "specimens of art from the ruins, with photographs of the architecture, showing that they were acquainted with the structure of the arch" (California Academy of Sciences 1873b:137).

On December 5 and 19 he read a long essay about his theories on seismology.  This work also appeared in an article, "The Causes of Earthquakes," published in 1872 in Van Nostrand's Eclectric Engineering Magazine.  In it Augustus wrote that the earthquake that devastated Peru in 1868 was a result of the action of percolated sea water and "chemical elements" that had reached a critical heat level.  They were made "incandescent" because that location of chemical activity coincided with "the voltaic arch formed by the electro-magnetic current passing between the sun as positive element and the earth as negative."

After his appearances before the California Academy of Sciences, Le Plongeon traveled to New York to lecture on his work in Peru and to try to sell several paintings he had acquired there.  In March 1871 he exhibited the three works, two by Bartolome Esteban Murillo and one by his teacher, the master Juan del Castillo.  The New York Evening Mail covered the event in a front-page article titled "Three Important Paintings from Peru."

Shortly after that, Augustus left for London to study an old Spanish manuscript in the British Museum.  Perhaps it would help unlock some secret of ancient New World civil-ization.  It was to be an eventful trip.  A visit to London and Paris always had to include some social obligations and diversions.  Sometime in the course of the year Augustus met Alice Dixon of Regents Park in London.  Though not yet 20, the well-bred young woman displayed remarkable poise and self-confidence.  Her questioning spirit must have caught Augustus' fancy, for the seasoned explorer, 25 years her senior, began courting her.  Her parents Henry and Sophia Dixon were impressed with him as a tough man of the world, yet of a gentlemanly, French background.  His descriptions of far-flung places and mysterious lost civil-izations captured Alice's imagination and intellect, and his kind hearted, and understanding manner captured her heart.

 Alice Dixon and Augustus Le Plongeon were married before leaving for New York in January 1873.  Alice bid farewell to her parents and four brothers and sisters, promising her dear sister Lucy that she would write often.

No sooner had Augustus returned to New York with his young bride than he became embroiled in controversy.  He contacted Harper's Brothers about publishing an article based on his research in Peru, intending to use the photographs E. G. Squier was to have carried to New York for him in 1863.  The publisher told him to consult with Squier, since they already had a contract with him, which included publication of the photographs Squier was now claiming as his own.

 Augustus was crushed by this apparent breach of confidence by someone he had collaborated with so closely.  He agonized over how to handle the situation.  Any hope of righting the matter slipped away within a few months, when Squier was declared mentally incompetent.  Augustus had nothing to prove that the photographs were actually his.  Even though he had used some of them in previous lectures at the California Academy of Sciences, they were not published or recorded anywhere in his name.  And they were undeniably in Squier's possession.

Squier must have had good connections, because it seemed not to matter that he had previously been involved in a similar controversy over stealing authorship from a col-league.  An 1847 report to the Smithsonian Institution about research done by Squier and Edwin H. Davis listed Squier as author and Davis as his assistant on a forthcoming book, Ancient Monuments of the Mississippi Valley.  Before the book came out, it took tremendous professional pressure from the Smithsonian authorities to persuade Squier to share the authorship with David.  Squier insisted that "only his generosity and friendship continued the partnership in which he alone produced anything" (Tax 1973:201).

 Squier's intransigence, however annoying, did not ruin all of Le Plongeon's plans in New York.  He appeared before the New York Geographical Society to read a scientific paper.  And he published a comprehensive manual of photography in Spanish that he had begun in Peru.  The 200-page book, Manual de Fotografia, covered all the materials and formulas used by a professional photographer of the 1870s.  By then the daguerreotype process Augustus had used in California was being supplanted by the wet collodion glass-plate negative process, which had become his standard practice in the field. Le Plongeon described in great detail the darkroom, cameras and their operation, preparation and action of chemicals, and the method of development, fixing, washing, and drying of negatives.  With as much precision as possible he described the art of preparing collodion glass-plate negatives.

The Manual included a trouble-shooting section and guidelines to help the photographer.  His final admonition, spoken from experience, was that the photographer needed to become totally familiar with his own camera equipment, chemicals, and the vagarious environment in order to make a perfect image.

With the photographic manual completed and professional and social contacts made in New York, the Le Plongeons were making plans to explore the archaeological ruins of Mexico.  They were anxious to delve into the secrets of the ancient Maya.