202 Mr. Talbot's Account of the 



of changing, while others differently prepared (and left unpre- 

 served) have grown quite dark in one tenth of that time, I 

 think this singularity requires to be pointed out. Whether 

 it will be of much value I do not know ; perhaps it will be 

 thought better to incur at first the small additional trouble of 

 employing the preserving process, especially as the drawings 

 thus prepared will stand the sunshine ; while the unpreserved 

 ones, however well they last in a portfolio or in common day- 

 light, should not be risked in a very strong light, as they would 

 be liable to change thereby, even years after their original for- 

 mation. This very quality, however, admits of useful appli- 

 cation. For this semi-durable paper, which retains its white- 

 ness for years in the shade, and yet suffers a change whenever 

 exposed to the solar light, is evidently well suited to the use of 

 a naturalist travelling in a distant country, who may wish to 

 keep some memorial of the plants he finds, without having the 

 trouble of drying them and carrying them about with him. He 

 would only have to take a sheet of this paper, throw the image 

 upon it, and replace it in his portfolio. The defect of this 

 particular paper is, that in general the ground is not even ; 

 but this is of no consequence where utility alone, and not 

 beauty of effect is consulted. 



§ 6. Portraits. 



Another purpose for which I think my method will be 

 found very convenient, is the making of outline portraits, or 

 silhouettes. These are now often traced by the hand from 

 shadows projected by a candle. But the hand is liable to err 

 from the true outline, and a very small deviation causes a no- 

 table diminution in the resemblance. I believe this manual 

 process cannot be compared with the truth and fidelity with 

 which the portrait is given by means of solar light. 



§ 7. Paintings on Glass. 



The shadow-pictures which are formed by exposing paint- 

 ings on glass to solar light are very pleasing. The glass itself, 

 around the painting, should be blackened ; such, for instance, 

 as are often employed for the magic lantern. The paintings 

 on the glass should have no bright yellows or reds, for these 

 stop the violet rays of light, which are the only effective ones. 

 The pictures thus formed resemble the productions of the art- 

 ist's pencil more, perhaps, than any of the others. Persons 

 to whom I have shown them have generally mistaken them for 

 such, at the same time observing, that the sti/le was new to them, 

 and must be one rather difficult to acquire. It is in these pic- 



