November 15, 1889.] 



SCIENCE. 



341 



There are certain peculiar features about the Blackman wheel 

 which entitle it to more than passing notice. It is said to be the 

 only exhaust or blast fan made which takes in air at right angles 

 to, as well as parallel with, its shaft, the peripheral flange increas- 

 ing its supply area by about sixty-six per cent. As the amount of 

 air removed and power required depend lipon the area of the feed 

 and delivery surfaces of air-moving machines, this wheel must 

 necessarily give a maximum delivery with a minimum absorption 



The fan, of course, may be driven by belt or electric motor, being 

 adapted to any desired motive power. 



The Merritt Type-Writer. 

 The little writing-machine shown in the accompanying illustra- 

 tion belongs to the class of type-writers referred to in these columns 

 last week, and known as lever or single-key machines. Th'e paper 

 being placed in position on the rubber roll or platen, and the latter 

 set at the proper point for beginning a sentence, the finger-key or 



THE BLACKMAN AIR-PROPELLER AND SOLANO HIGH-SPEED bl E^M-ENGINE. 



of power. The actual air-propelling capacity of the wheel, as given 

 by the manufacturers, is one million cubic feet per hour for each 

 horse-power used. These wheels are giving satisfactory results in 

 public halls, schools, theatres, mines, and other places, where they 

 are used to remove vitiated air or to supply fresh air. They range 

 in diameter from twelve inches to ten feet. 



The Solano high-speed engine also possesses some features 

 peculiar to itself. It has no dead centre, and can therefore be 



lever is moved to the letter it is desired to print, and pressed down 

 into a notch in the guide-rack. The types, which are the same as 

 ordinary printer's types, are carried in a type-holder attached to and 

 moved by the finger-key, and correspond in relative position with 

 the letters on the inde.x-plate. The movement of the finger-key to 

 any desired letter, therefore, brings the corresponding type to the 

 printing-point ; and the depression of the key into the notch both 

 locks the type-holder in position and forces the proper type up 



started with the crank in any position ; and the working parts are 

 entirely enclosed and protected from dust. The pistons, of which 

 there are three, are light and deep, and guide themselves in the 

 cylinders. The valve motion is very simple, a single rotary valve 

 being steam, exhaust, and relief valve all in one. The lubrication 

 is entirely automatic, and, up to a speed of four hundred revolutions 

 per minute, the only lubricator required is that on the steam-pipe, 

 whence the oil is forced to all the parts needing it. This engine 

 and the wheel or fan described, to the shaft of which it is attached, 

 make a self-contained, compact, and efficient ventilating-machine. 



into contact with the paper. Accurate alignment is secured by 

 means of a type-guide. 



This machine prints capitals, small letters, punctuation-marks, 

 figures, etc., and its work is as clear and legible as that of the ex- 

 pensive key-board machines. It uses 7S ordinary printing-types, 

 which are inexpensive to replace when worn out. The types are 

 inked automatically, and no ribbon is used. A speed of sixty 

 words a minute is claimed for it ; the speed-test, of course, being 

 made by the frequent repetition of a short sentence with short 

 words, as in all type-writer tests of the kind. 



