Latitude observations at Pulkovo came into existence about 1840 year and were made with the Repsold transit instrument in the first vertical and with the Ertel vertical circle. W. Struve in 1840—1856 and H. I. Peters in 1842—1849 were the first observers on these instruments. In the paper various series of latitude variations obtained from these observations by M. O. Nuren, B. Wanach, A. A. Ivanov, I. V. Bonsdorf and A. Ya. Orlov are collected and analysed. We give the results for investigations of special features of Chandler polar motion during this interval which were obtained by S. Chandler, A. A. Ivanov, H. Kimura, A. Ya. Orlov, and N. Seciguchi. Our purpose was to search for the earliest series of Pulkovo latitudes and to analyse them to appreciate the possibility of their use for the investigation of the polar motion during the maximum interval of realization. Some different methods were used to extract and analyse the sum of chandler and annual latitude variations. The supplement presents the set of the Pulkovo latitude variations for 1840—1848 years which can be used to prolong the latitude variation set back to 1840.