X. MODELS, ETC. 375 



This is accomplished by a set of counterpoises, equal in the aggregate to 

 the whole weight of the shutter, which are lowered one after another into the 

 place prepared for them. When the shutter is half open all the weights are 

 deposited; the shutter being then balanced in itself. The chains then lap 

 round a roller prepared for them, and as the shutter opens still further the 

 weights are again raised up one by one as the shutter gets heavier and 

 heavier towards the back. 



If desired, this form of roof can also be made to open beyond the zenith by 

 placing a pair of doors at base of shutter " chase," which open automatically, 

 and allow the shutter to roll back. 



1912a. 11 Photographs of the buildings of the Observatory 

 and its principal instruments. The Pulkowa Observatory. 



1912b. 10 Photographs of several auxiliary instruments 

 lately constructed by M. Herbst, at the mechanical workshop 

 of the Observatory. The Pulkowa Observatory. 



$ 1912c. Photographs of Mr. Newall's Observatory. 



J. Norman Lockyer , F.R.S. 



1912d. Photograph of Galileo's Tribune at Florence. 



J. Norman Lockyer , F.R.S. 



1912e. Photographs of the Old ^Astronomical Circles 

 at Delhi. Mrs. Norman Lockyer. 



1912f. Photographs of the Lamp in the Cathedral at 

 Pisa (interesting in connexion with Galileo's observations). 



Mrs. Norman Lockyer. 



1914. Three Photographs of Astronomical Universal 

 Instruments. F. W. Breithaupt and Son, Cassel. 



Astronomical universal instrument, portable. The movable circles have 

 each two magnifying lenses for reading the seconds ; the vertical circle is 

 33 cm., and the horizontal 50 cm. in diameter. The broken telescope has an 

 aperture of 67 mm. and a focal distance of 80 cm., and is illuminated through 

 the axis. The instrument revolves on the vertical axis ; the horizontal axis 

 is balanced on one plate only, and is invertable on spring rollers. One level 

 rests on the horizontal axis, a second is attached to the carrier of the magni- 

 fiying lens, and a third can be inverted on the same. The second vertical axis 

 which serves as a counterpoise is graduated. The instrument itself was made 

 in the year 1873 for the Japanese Government in Yokohama. 



(2.) Astronomical universal instrument, portable. 



This instrument is provided with two movable circle**, of 25 cm. diameter, 

 each having two magnifiers, with a side telescope of 27 mm.' aperture and 

 opposing vertical circle, the carrier of the magnifying lens being in the middle. 

 By this arrangement the upper part of the instrument is kept low ; it has 

 also the advantage that, without alteration of position, the telescope, the two 

 circles, as well as the numerating circle, can be observed. This instrument 

 was constructed in 1875 for the Royal Mining Academy at Schemnitz. 



(3.) Universal instrument, portable. 



The circles are 20 cm. in diameter, the vernier reads to 10 seconds, the 

 telescope of 40 in. aperture is at the side, the azimuth circle is movable and 



