First and foremost as a source of information is Lachlan Macquarie's personal journal:
MACQUARIE, Lachlan Journal: 18 March 1807 - 17 October 1807.
Original held in Mitchell Library, Sydney.
ML Ref: A771 pp.1-264 [Microfilm copy: CY Reel 300 Frames #430-696].
Commencing at Bombay
on Wednesday 18th. of
March 1807 — by
Lt. Colonel Mc.Quarie
H.M. 73d. Regt.
Holograph manuscript in Macquarie's hand.
Paper size: 18.5 cm x 11.5 cm. [approx]
The mss. is no longer in its original binding. The paper stock and page size changes at 105-106ff. [p.207] (i.e. on Thursday 10 September 1807, in St. Petersburg) with the use of a lighter, more transparent paper, and resized to 18.5 cm x 12.7 cm. [approx]. There is a heavier paper stock with a more pronounced paper grain for 1-104ff, as well as some circumstantial evidence that the original mss. pages may have been trimmed for mounting in the current Mitchell Library volume.
The original manuscript consisted of 134 unnumbered loose-leaf pages, written double-sided [except the cover page which is single-sided] and mounted in sheets bound in a red leather folio album. There is a possibility that the original sheets may have been half-folded by Macquarie [cf. letter sheets] and kept in date order.
A page numbering sequence appears to have been added at later date, presumably by Mitchell Library staff in the post-1914 period. There are two numbering sequences: one in pencil on the front of each mss. sheet, commencing with the Arabic numeral '2' on first entry for 18 March 1807, but not on the verso sheet [pp. 2-134]; the second sequence begins (in pencil) on the mount board with the Arabic numeral '1' on the first entry for 18 March 1807 and the sequence is continued on the verso side of each page until the end of the mss. [pp. 1-264].
Structure of the Journal
Macquarie's journey from Bombay to London took 6 months and 24 days and by his own personal calculation he had traversed 6400 miles by sea and land. A close examination of Macquarie's journal indicates that out of a total of 214 days there are individual journal entries for 137 days. The 77 days that have been omitted generally coincide with periods of physical inconvenience while travelling by sea or when confined in quarantine.
Lachlan Macquarie in Persia
The Persian section of Macquarie's journal commences on Thursday 20 May 1807 at Qasr-e-Shirin and concludes thirty-eight  days later [on 27 June] with Macquarie's departure from Bandar-e-Anzali. He left Persia on board a small four-oared sailing boat travelling northwards across the Caspian Sea towards the Russian-held island of Sarrey and the important trading port of Baku. This voyage took three and a half days to complete.
There are journal entries for every day in Persia except 3 June, and the internal evidence suggests that the entries were recorded daily or, at the least, within 24 hours of the events described. In general this task would have been undertaken during daylight hours when the caravan was avoiding the heat of the day and the travelling party was resting up in preparation for the next stage of the night journey. Travel through the mountains was arduous and tiring - not least because, at times, the caravan party was climbing at high altitudes or the road was narrow or dangerous.
The first direct references to the Qajar Court appear in Macquarie's journal on 5 June near the town of Razan when he was summoned to attend the Shah in Tehran or at his summer camp.
At 4 pm on 18 June 1807 Macquarie wrote a letter from Sangally, near Qazvin, to John Hine, the Acting British Resident at Baghdad. He had reached the summer camp of Fath 'Ali Shah and Macquarie stated that:
"...there are three frenchmen now at this Court in Diplomatic characters - who are day and Night importuning the Shaw and his ministers to break with the English openly and to conclude a Treaty of alliance with the Great Nation in order to ruin the English and Russians. This the sha and his ministry have hitherto resisted, and both Viziers declare their resolution never to break with their good faithful friends the English. For further particulars on this interesting subject, I must refer you to Minas when he returns to Bagdad. We proceed direct from hence to Anseley on the Caspian which is said to be only 8 days Journey, and the Vizier informs us that we shall get shipping there to carry us direct to Astracan. —"
The content of the letter reveals clearly the imperial dimension to Macquarie's journey: the presence of representatives of the Emperor Napoleon at the Qajar Court and the possibility that French officials might negotiate an alliance that could threaten British interests in India.