Verbal voting lasted until 1870, when Parliament finally agreed to adopt the secret ballot.
At the 1871 general election, each voter was given a printed ballot paper listing the candidates in their electorate. They marked the paper in private behind a screen and then deposited it into a locked ballot box. This established a method of voting that has been more or less the same ever since.
Secret voting was important because it reinforced the idea that the vote was an individual right, which each elector should be free to exercise according to their conscience, without fear of intimidation. This helped to open the way for the later expansion of the franchise to all adult men - and eventually to women.
The secret ballot and other reforms also did much to improve election-day behaviour, and since the 1870s voting in New Zealand elections has usually been orderly and above suspicion of corruption.