Download letters in ZIP packages:

TXT XML
1730s BC_173_txt.zip BC_173_xml.zip
1740s BC_174_txt.zip BC_174_xml.zip
1750s BC_175_txt.zip BC_175_xml.zip
1760s BC_176_txt.zip BC_176_xml.zip
1770s BC_177_txt.zip BC_177_xml.zip
1780s BC_178_txt.zip BC_178_xml.zip
1700s (undated) BC_17x_txt.zip BC_17x_xml.zip
All BC_all_txt.zip BC_all_xml.zip