A recent search of the online index at ancestry.com for the 1840 Ohio census for "Josl*" turned up eight results. Jonas Joslin was not among them and there was no "Joslin" family listed in Delaware County, Ohio.
Jonas Joslin is indexed as 'Jonas Joflin' in the ancestry index. I finally found him in the index by searching for first name of Jonas and last name blank in Delaware County, Ohio. A correction has been submitted to ancestry to aid others in finding him.
Liberty Township, Delaware County, Ohio - Page ?? I have "30" written in my notes, probably from the microfilm. The ancestry image has "0100" stamped along the right side. There is "186" written in the upper right corner but it is crossed through. It is Image 3 of 6 for Liberty Township.
In the 1850 census, Jonas Sr. is listed as head of the household with Jonas Jr. and his family in residence. Based on that, I've made the assumption that in 1840, Jonas Sr. was the head of household and Jonas Jr. and his family resided with him. But I could be wrong ;-) Ruth, the wife of Jonas Sr. had passed away on August 27, 1830.
The probable household of Jonas Joslin in 1840:
- 1 male under 5 [1836-1840... William, son of Jonas Jr., born 1836]
- 1 male 10-14 [1826-1830... John, son of Jonas Jr., born 1828]
- 1 male 30-39 [1801-1810... Jonas Jr. born 1807]
- 1 male 60-69 [1771-1780... Jonas, Sr. born 1769]
- 3 females 5-9 [1831-1835... 3 daughters of Jonas Jr., Lucretia, Nancy and Jane]
- 2 females 30-39 [1801-1810... Fanny, daughter of Jonas Sr., born 1810, and Lucy, wife of Jonas Jr., born 1807]