If properly treated, a negative remains good for years, and will serve for an indefinite number of positives or true photographs. 伯莎M.克拉克.科学通论.
In 1880 Muybridge produced, in San Francisco, the ‘Zoopraxiscope,’ which projected pictures (on glass positives) on a screen. 佚名.神奇的知识之书.
At the end of the scene the negative is developed in the ordinary way, and is then ready for use in the printing of the positives for sale. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
Three sets of each of these positives were made, and all put into separate test tubes with a uniform type of negative element. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
This completed the negative or stencil from which the positives are printed by passing rays of light through it upon sensitive paper. Edward W. Byrn.十九世纪发明进展.