The consensus of scholars is that Poe assembled Arthur Gordon Pym in a series of stages under financial and deadline pressure, that his conception of the novel changed at each stage, and that the published text represents an unfinished and unpolished draft that Poe lacked the time or inclination to revise into a coherent whole.
Neither the chronicle of the voyage of the Grampus nor the sequence which follows Pym’s rescue by the Jane Guy is consistent even within itself. Each part promises actions which never occur; each has confusing shifts in characterization; each contains many discrepancies in factual detail. The only explanation which will account for this unusually flawed text is that Poe worked on it at several periods between the end of 1836 and the early summer of 1838, that he changed his mind several times about the direction of his story line, and that he made a hurried but inefficient attempt to turn his disconnected narrative into a whole at the very moment when the volume was being put to press.
J. V. Ridgely and Iola S. Haverstick (1966). ‘Chartless Voyage: The Many Narratives of Arthur Gordon Pym’. Texas Studies in Literature and Language 8:1, p. 63.
The first section of the text, the childhood of Pym and the voyage of the Grampus, was begun in 1836 as a serialized story for the Southern Literary Messenger where Poe was assistant editor. At this point Poe’s conception of the work seemed to be that of a true-life sea adventure, in the manner of Richard Dana’s Two Years Before the Mast (1834) or Frederick Marryat’s Mr Midshipman Easy (1836). Two installments were published, in January and February 1837, but Poe resigned (or was sacked) from the Messenger and stopped work on the project.
Later, struggling financially in the Panic of 1837, Poe sold the novel to Harper and Brothers, and wrote the Jane Guy section. At this point Poe’s conception seemed to be a pastiche of a journal of oceanic exploration, like Benjamin Morrell’s popular A Narrative of Four Voyages (1832). In fact, much of the material in the Jane Guy chapters is copied from Morrell and other authors, with only a little in the way of paraphrase. For example, compare these two descriptions of the albatross:
This [the albatross] is one of the largest and most formidable of the South Sea birds; being of the gull kind, and taking its prey upon the wing. Like many other oceanic birds, the albatross never comes on land except for the purpose of breeding; when the attachment that exists between it and the penguin is evinced in many remarkable instances; indeed it seems as firm as any that can be formed by the sincerest friends. Their nests are constructed with great uniformity near to each other; that of the albatross being always in the centre of a little square, formed by the nests of four penguins.
Benjamin Morrell (1832). A Narrative of Four Voyages, p. 50. New York: J. & J. Harper.
The albatross is one of the largest and fiercest of the South Sea birds. It is of the gull species, and takes its prey on the wing, never coming on land except for the purpose of breeding. Between this bird and the penguin the most singular friendship exists. Their nests are constructed with great uniformity upon a plan concerted between the two species—that of the albatross being placed in the centre of a little square formed by the nests of four penguins.
Edgar Allan Poe (1838). The Narrative of Arthur Gordon Pym, chapter XIV. New York: Harper and Brothers.
The shameless copying in the Jane Guy chapters suggests that at this point in the composition of the novel, Poe was lacking in time or motivation. However, in the Spring of 1838 the United States Exploring Expedition was authorized by Congress, and with the country enthused by the prospect of Antarctic discoveries, Poe was evidently keen to catch the coat-tails of public sentiment, and accordingly in chapter XVI the narrative changes course for the South Pole.
Subtantial passages in this part of the narrative are copied from Jeremiah N. Reynolds’s Address on the Subject of a Surveying and Exploring Expedition to the South Seas (1836) in which he had stated the case for the expedition. Compare these two descriptions of Cook’s first crossing of the Antarctic Circle:
In the year 1772, Captain Cook, in the Resolution, accompanied by Lieutenant Freneau, in the Adventure, embarked on his first voyage in search of a southern continent. Having, in December, attained the fifty-eighth degree of south latitude, in longitude 26° 57′ east, he fell in with narrow fields of ice, running north-west and south-east, from six to eight inches in thickness, and appearing to have been formed in bays or rivers. This ice was in large flat pieces, and, in some instances, packed so closely, that the vessels, with difficulty, passed through it. Here were seen great numbers of penguins, which, with other coinciding circumstances, induced the supposition of land being in the vicinity. This opinion was afterwards shown to be erroneous, the ice proving to be unattached to any shore. In latitude 61° 12′, the voyagers met with considerable ice-islands, many of which were passed unseen, by reason of the thick haze. Three degrees further south, in longitude 38° 14′ E., they had mild weather, with gentle gales, for five days; thermometer thirty-six, and prevalent winds east and east by south. In January, 1773, they crossed the Antarctic circle in latitude 66° 36′ 30″; and, on reaching latitude 67° 15′, found the ice closed the whole extent, from east to west-south-west, and no indication of an opening. This immense area was filled with ice of different kinds, high hills, broken masses compactly pressed together, and field ice. A float of the latter, to the south-east, appeared sixteen or eighteen feet above the water, and its extremities could not be seen from the mast head. As the summer of that region was nearly half spent, and it would have taken some time, even if practicable at all, to get round the ice, Captain Cook determined to retrograde.
Jeremiah N. Reynolds (1836). Address on the Subject of a Surveying and Exploring Expedition to the South Seas, p. 90–91. New York: Harper and Brothers.
In 1772 he [Captain Cook] sailed to the south in the Resolution, accompanied by Lieutenant Furneaux in the Adventure. In December he found himself as far as the fifty-eighth parallel of south latitude, and in longitude 26 degrees 57′ E. Here he met with narrow fields of ice, about eight or ten inches thick, and running northwest and southeast. This ice was in large cakes, and usually it was packed so closely that the vessel had great difficulty in forcing a passage. At this period Captain Cook supposed, from the vast number of birds to be seen, and from other indications, that he was in the near vicinity of land. He kept on to the southward, the weather being exceedingly cold, until he reached the sixty-fourth parallel, in longitude 38 degrees 14′ W. Here he had mild weather, with gentle breezes, for five days, the thermometer being at thirty-six. In January, 1773, the vessels crossed the Antarctic circle, but did not succeed in penetrating much farther; for upon reaching latitude 67 degrees 15′ they found all farther progress impeded by an immense body of ice, extending all along the southern horizon as far as the eye could reach. This ice was of every variety—and some large floes of it, miles in extent, formed a compact mass, rising eighteen or twenty feet above the water. It being late in the season, and no hope entertained of rounding these obstructions, Captain Cook now reluctantly turned to the northward.
Edgar Allan Poe (1838). The Narrative of Arthur Gordon Pym, chapter XVI. New York: Harper and Brothers.
In summary, the reasons for the abrupt shifts of style are that Poe did not carry through a fixed plan for the novel, but changed direction with changing circumstances, and that he responded to the pressure of deadlines by copying long passages out of Morrell, Reynolds, and others, resulting in clashes between Poe’s own narrative style and that of his sources.
At the beginning he was concerned only in the creation of a verisimilar voyage narrative, in which the character of young Pym was to be as important as his adventures. In the later stages—having failed to finish his planned cruise before he came under the influence of renewed interest in Antarctic exploration—he tried to transmute his protagonist into an older and self-effacing reporter of incredible but actual discoveries. As a result, the book was thrown wildly off balance, and much of the earlier material was rendered irrelevant in terms of preparation for the final scenes.
Ridgely and Haverstick, p. 80.