August 28, 1885.] 



SCIENCE. 



167 



of the individual. The combination of a pho- 

 tograph of a person at one age, with that of the 

 same person at a different age, is very much 

 like what the person looked at an intermediate 

 age. The effect of hair, costume, etc., often 

 spoils the result.^ 



While the combination with an ordinary 

 stereoscope is very satisfactory, there are a 

 few advantages in using the original form of 

 the instrument as it was invented by Wheat- 

 stone. This consists of two mirrors set at 

 right angles, and two bars running out per- 

 pendicularh' to the faces of the mirror. Along 

 these bars uprights, holding the photographs, 

 can be moved. One e3'e 

 looks into each mirror, and 

 the combination of the two 

 images takes place. Dif- 

 erences in size of the pho- 

 tographs can be accounted 

 for by moving the larger 

 one farther off, and the 

 smaller one nearer. As 

 soon as the two images, 

 as seen side by side, are 

 of the same size and posi- 

 tion, the bars are moved on 

 their common axis until 

 the images coalesce. The 

 composite thus formed is 

 even better than the Brew- 

 ster stereoscope, and the 

 arrangement lends itself 

 to a greater variation in 

 the experiment. Two cau- 

 tions may be useful : 1°. 

 The head must not be 

 moved. A prong of wood 

 attached to the instrument, 

 and held between the teeth, 

 will be an aid. 2°. The il- 

 lumination of the two pic- 

 tures must be alike, or else 

 the more strongly illuminated will give the 

 character to the composite. 



While composite photography has always 

 made use of photographs, there is no impossi- 

 bility in making a composite directly from the 

 original sitters. A Philadelphia i^hotographer 

 has been successful in producing a composite 

 of two sisters from actual life. The method 

 is, doubtless, more troublesome than the usual 

 one. With the Wheatstone stereoscope, one 

 can combine living faces by having two per- 

 sons assume appropriate positions ; and, as 

 before, by guiding the movements of their 



1 I would sugfi^est that this method offers a means of studying 

 the nature of the expression of the emotions. 



heads, uniting the images in the mirrors. Both 

 the full face and the profile give a peculiar and 

 lifelike effect. 



The most common difference in the position 

 of photographs, as ordinarily taken, is the di- 

 rection of the head ; i.e., whether more of the 

 left or the right side of the face is shown. 

 Two photographs, looking in opposite direc- 

 tions, cannot be combined by any of the above 

 methods. A simple device overcomes the dif- 

 ficult3^ A piece of mirror is held directly in 

 front of the face between the two eyes. The 

 two pictures are set side by side ; one is looked 

 at directly with one eye, while the other is 

 seen reflected, and, of 

 course, reversed in the 

 mirror. By moving the 

 photograph until its reflec- 

 tion coincides with the 

 other, a perfect blending 

 takes place. 



I have tried combina- 

 tion by means of the zoe- 

 trope. Simple figures can 

 be satisfactorily' combined ; 

 but so complicated a de- 

 sign as the human face, is 

 accompanied b}^ a vague- 

 ness of outline and detail 

 which render the process 

 useless. By using five or 

 six of each of the two pho- 

 tographs to be combined a 

 distinct face is seen. Even 

 then the result is not nearly 

 so good as in the stereo- 

 scopic combination. Be- 

 sides, there is no way of 

 accounting for small differ- 

 ences in the photographs. 

 In combining several pic- 

 tures, one gets nothing but 

 a Jumble of faces. 

 The fatal objection to all these hand-pro- 

 cesses is, that but two photographs can be 

 combined at once. To unite the resultant com- 

 posite of two or more stereoscopes, is, per- 

 haps, possible, but would certainl}^ prove ver}' 

 troublesome. An apparatus, that, by a s^'stem 

 of mirrors, would superimpose a series of im- 

 ages, suggests one method of extending the pro- 

 cesses above described. Joseph JA^TROW^ 



A COMPOSITE PORTRAIT OF THE OF- 

 FICERS OF THE ASSOCIATION. 



The accompan3ing photo-engraving is a 

 composite of the photographs of the highei 

 officers present at last year's meeting of the 



