428 REPOKT— 1892. 



4. Conlson's slide rule. 



5. The cubing slide rule. 



6. The timber contenting slide rule. 



In addition to these, Favaro adds twenty-nine others, of which the 

 following are a few referring to mechanical science : — - 



1. Hoare's sliding rule, London. 



2. Palmer's computing scale, New Tork. 



3. Fuller's computing telegraph. New York.' 



4. Logarithmic disc of Sonne, Paris. 



5. Lalanne's rule, Paris. 



6. Scale and rule of Mannheim. 



7. Soldati's rule, Turin. 



8. Arithmetograph of Qnintino Sella, Turin. 



9. Cylindrical arithmetograph of Porro, Turin. 



10. Everett's proportion table, London. 



11. Boucher's calculating circle, Paris. 



12. Routledge's slide rule, London. 



13. Hawthorn's slide rule, London. 



14. Stanley's builders' calculating rule, London. 



15. Tavernier Vinay et Tavernier Gravet's calculating rule, Paris. 



16. Coggeshall's slide rule, London. 



17. Bradford's sliding rule, London. 



18. E. Peraux's calculating rule, Nancy. 



19. Dennert and Pape's calculating scale, ' Deutsche Bauzeitung,' 



vol. viii. p. 136. 



20. Eschmann's calculating scale, Aarau. 



21. Moinot's calculating rule, Paris. 



22. Castigliano's arithmetograph, Turin. 



This list suffices to show that almost every kind of variation may be 

 made in the form of slide rules ; there are a few others, which do not 

 appear to be described in any book in this country, which may be 

 mientioned, viz. : — 



1. Boucher's patent calculator, which is only of the size of an ordinary 

 watch. It has faces back and front. On the front is a logarithmical 

 scale in four lines, being on the whole equal to 15 inches of straight scale. 

 This produces a more open scale than the ordinary slide rule. There are 

 two index hands, one on the central axis, and one fixed upon the side of 

 the case. The central hand revolves by the turning of a milled head at 

 the side of the case. The entire dial revolves by the milled head upon 

 one face ; any operations in addition, subtraction, multiplication, division, 

 and proportion can be performed to four places of figures. And upon the 

 other face trigonometrical calculations, viz., logarithms, powers, and 

 roots. 



2. Hudson's horse-power computing scale may be mentioned as a con- 

 venient little pocket instrument with two sliding scales. By this means 



' The following notice appeared with this instrument :— ' A most wonderful and 

 extraordinary instrument, by which business questions of every possible variety are 

 instantly performed ; a safe and speedy check to avoid vexatious errors, and afford at 

 the same time a greater amount of practical business knowledge than can be obtained 

 from ten times the cost of the work.' Sold only by subscription. John E. Fuller, 

 proprietor. New York. 



