BAIRD &TATLOCK. (LONDON) LTD. 



1641 

 1641 T Demonstrator's and Student's Microtome. 



This handy microtome is chiefly adapted for rapidly preparing sections tor demonstrations or diagnosis. The 

 knife is carried in a circle about an axis, journalled between two pointed screws, and the knife is so fixed as to give 

 an oblique cut. 



The workmanship of the microtome is such that in point of stability and certainty of action, it satisfies the 

 highest requirements, so that embedded objects and frozen objects may be cut with equal precision. Freezing 

 may be effected with the aid of carbon dioxide and ether. Being simple in construction and management, and 

 correspondingly inexpensive, it is well adapted for the use of students. 



It is attached to a table by means of a rectangular screw clamp, which is continued above into a rigid casting 

 provided with two hardened centre screws, between which swings the axis of the knife-holder. This arrangement 

 lias proved entirely satisfactory in the case of small microtomes. Should the knife-holder show any signs of play, 

 loosen the nut at the upper centre by means of a tommy, take up the slack between the points, and re-tighten the 

 nut. The knife-holder has the form of a bridge, and by reason of its outer form is extremely rigid, so that the knife 

 cannot yield or vibrate. The knife is fixed by means of set screws in two recesses on the right and left side of the 

 knife-holder. 



The vertical branch of the teeth clamp carries the object slide, which moves within dovetails. The micro- 

 meter screw, for raising and lowering the slide, is journalled within a rectangular frame. The nut of the micro- 

 meter screw is bi-valve and adjustable by a screw. The spindle carries a serrated disc. During the rotation of 

 t lie knife-holder, the serrated wheel advances after each cut through a number of teeth, determined by the position 

 of the stop. The adjustment is effected by the displacement of the lever, which carries the pointer. Each tooth 

 corresponds to an elevation of the object, amounting to 0.005 millimetres. By turning the milled head below, the 

 object may also be raised by hand. In this case the thickness is indicated by divisions inscribed on the disc. Each 

 interval on the wheel corresponds to o.ooi millimetres. To return the slide to its original position, the ratchet pawl 

 should be disengaged, whilst with the other hand the screw should be worked back. 



The object clamp slips into the hole bored into the object slide, and fixes with the aid of a set screw. 



With knife, blade 8 cm., and without freezing apparatus 



1642 T Carbonic Acid Freezing Apparatus for microtome No. 1640. 



This apparatus is attached to the cylinder by means of a flexible metal tube. By its means any preparation 

 may be frozen within a few minutes. Over the ether freezing apparatus it has the advantage, that the state of 

 congelation is reached much more rapidly, and may also be maintained for a longer period than is the case with 

 ether. The connection between the gas bottle and cylinder is established by means of a flexible metal tube, which 

 greatly facilitates the attachment and detachment of the apparatus. 



The gas cylinder, with its valve downwards, is placed on its stand. Any water which may be present is thus 

 made to collect, and may be blown out after an hour's standing. The tube may then be attached to the gas cylinder 

 by means of its union. In the case of freshly filled gas cylinders the elimination of the water should never be 

 omitted, since in the event of its passing into the apparatus it would interfere with its proper working. After use 

 the valve on the gas cylinder should promptly be closed 



3 17 

 1 10 



SO CHEMICAL AND SCIENTIFIC APPARATUS AND PURE CHEMICALS 



