Dhammathat Cave is mentioned in most of the colonial literature.
The spelling varies in almost every report, and variations are Dhammathat Cave, D'ammabat Cave, Damatha Cavern, Buddha-cave at Dhammathat, Dhammethat, Dhammathat-Höhlen, D'ammabâ-Cave, Buddha-Cave bei Dhammathat (Damatha), Dhamathat, D'ammaba Cave, D'ammabâ Cave, D'ammabâ ku, Damathat Cave, Grotte de Dhammatat, Buddha Cave (à Dhammathat ou Damatka ou Damotha), Damatha Cave, cave at Dumathat………. thanks to Helmut Steiner for typing this list!
In 1835 the American missionary Malcolm visited the two Dhammatat Caves, close to the Gyaing river (Malcolm 1837).
Around 1836 Capt. W. Foley visited the Dhammatat Caves (Farm Caves).
Temple describes the cave in 1893. He had visited with Oertel in April 1892. "The D'ammaba Caves, 18 miles from Maulmain on the Jain (Gyaing) River." It is confusing as he writes that "Farm Caves, about 10 miles from Maulmain on the A'taran River". However looking at the map, Farm Caves are closer to the Gyaing River.
Temple says "The D'ammaba cave is reached by boat or launch, up the Jain river, 19 miles, and contains about 1000 images, of which 100 are in good order, and one chaitya".
From British Burma gazetteer (1879) -
DHAM-MA-THA.—A small village in the Amherst district on the left bank of the Gyaing, opposite a large grass and tree-covered island lying about sixty yards off, seventeen miles above Maulraain. To the south of the village is an extensive outcrop of limestone rocks covered with dense tree forest and pierced by a large cave with the walls and roof highly ornamented with figures in red and gold of Gaudama Booddha and of Rahan and the floor covered with images. [Thanks to Sergey Shugrin in Russia for sending this]
It is almost certain that Dhammathat Cave is the same as Farm Cave (although looking at Google Earth it could be further upstream from Farm Cave).
See also Farm Caves - Kayon & Saddan
Survey by Temple
Foley, Capt. W. (1836): Notes on the geology etc. of the country in the neighbourhood of Maulamyeng (vulg.
Moulmein). - J. Asiat. Soc. Bengal, 5, p. 269-281.
Malcolm, Rev. H. (1837): Account of the Caves near Moulmein. - Asiatic Journal N.S., 24, Pt. 2, p.10.