Ron Guth: In 1795, mint engravers reduced the size of Liberty's head on the half cents. The earliest versions of the 1795 half cent feature a lettered edge. A statutory reduction in the weights of the planchets in December of 1795 forced the removal of the edge lettering because the planchets became too thin to accommodate any edge ornamentation. The 1795 "Punctuated Date" was caused by a small, comma-like defect that appears beneath the 1 and the 7 of the date. Other 1795 varieties include a date where the letter I takes the place of the numeral 1. The 1795 and 1796 "No Pole" varieties occurred when the engraver forgot to add the pole that supported Liberty's cap. Both 1796 varieties (No Pole and With Pole) are rare and desirable. 1797 half cent varieties include the 1 over 1 (first punched too high), the "Gripped Edge" (an extremely rare experiment of a crude edge marking), and the "Lettered Edge" (further proof that the planchets were too thin to receive egde lettering). No half cents were produced in 1798 and 1799, after which the Draped Bust design replaced the Liberty Cap theme.
Sources and/or recommended reading: "American Half Cents - The 'Little Half Sisters' (Second Edition)" by Roger S. Cohen, Jr.
"Walter Breen's Encyclopedia of United States Half Cents 1793-1857" by Walter Breen