TRANSFUSION OF BLOOD. 



TRANSIT, OR TRANSIT INSTRUMENT. 



poaitive side of one with that of the other ; bat, since only cosines are 

 used, the direction of revolution i* immaterial. If both system* be 

 rectangular, and if they have the same origin, we have two sets of 

 equations, each of which follow* from the other, one set being in each 

 column ; the meanings of a, a', ftc. being a* before, 



T, = oar + a'y + a"z 



o + a" -r a" = 1 



07 -r 07' + 0V = 

 70 + ya' + 7V = 



i, -i* +y'y 



+ 7* -1 

 +V =1 



a"a + 0"0 +7*7 "0 

 aa' + 00 1 + ti = 



Besides which, each of the quantities a, o', ftc. may be expressed in 

 terms of the others, as follows : 



0y- -,'ff 

 0" 7 - 7*0, 

 0y - 70", 



= ya"- Y' 

 * = 7" - "7. 

 ff - 7* 1 - 7', 



7 = a'0"- 0V 

 V - <O - 0" 

 7" = ^ -/W- 



For the mode in which these nine quantities are made to depend 

 upon three, we must refer to works on mechanics, in which such reduc- 

 tion is particularly useful. We avoid giving it here, because trifling 

 differences exist in the manner of taking the quantities to functions of 

 which all the rest are to be reduced, so that no set of equations can be 

 given which can be called universal. So far as we have gone, the 

 expressions of all writers are the same, though the letters used are not 

 always alike. 



TKANSFUSION OF BLOOD is the operation of transferring the 

 blood of one animal into the blood-vessels of another, and is sometimes 

 beneficially employed for reviving those who are nearly dying after 

 severe htemorrhage. The operation had long been used as a means ol 

 experiment, and in the vain hope that by injecting the blood of a 

 healthy man or animal into the vessels of a diseased one, the health ol 

 the latter would be restored ; but it had rarely been employed for its 

 only useful purpose till Dr. Blundell, after a long series of well-con- 

 ducted experiments on animals, proved that it might be safely and 

 advantageously employed in men. His observations are published in 

 his ' Physiological and Pathological Researches ; ' and since his reviva 

 of the operation, the lives of many persons have been saved who were 

 in all probability, dying from the loss of blood during or after surgical 

 operations, during gestation, and in other circumstances. The opera 

 tion has, indeed, often failed ; it has often been unnecessarily per 

 formed ; and it* performance is not unaccompanied by danger to the 

 patient ; but still there is sufficient evidence of its high utility in cases 

 which, without it, would have been quite or nearly hopeless, to warrant 

 its being resorted to under the guidance of a sound judgment. 



The chief instruments employed in the operation are a syringe, with 

 double pipe*, a baain of appropriate form, and a fine tube fixed on one 

 of the pipe* of the syringe. One of the veins of the arm of the p.iti. nt 

 being opened just sufficiently to admit the point of the tube, and tixet 

 by a probe, blood must be drawn through a free opening in the vein o 

 some healthy person, and as it flows into the basin must be slowh 

 licked up, without any mixture of air, by the syringe. When the 

 syringe U filled and carefully cleared from all air l.y forcing blood u] 

 to the very point of the tube, the latter must be introduced into the 

 patient's vein, and the blood steadily and slowly injected. Four or 

 five ounce* are often sufficient to revive a patient, and if they product 

 head-ache, flushings of the face, tendency to fainting, and other unplca 

 ant symptoms, the transfusion should be arrested ; but if not, the 

 injection should lie continued till it produce* some good effect, or til 

 a pint of blood ha* been transfused. Beyond this it is not safe to carr 

 the operation, nor is it likely to be beneficial. A second or a third injec- 

 tion may be employed when the state of the patient seems to rende 

 it necessary. 



The experiment* of transfusing the blood of various animals intc 

 the vessel* of man proved only mischievous ; and those of transferring 

 the blood of an animal of one specie* to the blood of another specie 

 are of too little interest and have produced too few general result* to 

 be worth recording here. The injection of various medicinal substances 

 into the vein* has been tried, but its effect* are not sufficiently differ 

 cut from those produced by the ordinary mode of taking medicine 

 to render it advisable to submit to an operation which is itael 

 dangerou*. All the important fact* relating to the subject may be 

 read in an article on Transfusion, l.y l>r. K.iy. in the ' Cycloptodta o 

 Practical Medicine,' and in the works from wl.n-li ho quote*. 



TRANSIT, or TRANSIT INSTHr.MKNT < /*,trnme*t drt Paaagn\, 

 was invented by Romer about the year 1690. The description 

 found at page 47 of the ' llanis Aatronotnito,' by his pupil, Horrebow 

 Havnia), 1735; and we recommend the perusal of this book, whic 

 contain* an account of Romer'* inventions and method*, to all those 

 who, reading Latin with moderate ease, feel a desire to learn the origi 

 of modern practical astronomy, 



The object of the present article i* to gire *uch an account of the 



transit a* wiU enable any one to use it with tolerable success. Those 



who wish for more (wfect information must consult the introductions 



o the Greenwich. K6nigsburg, Dorpat, Cambridge, Edinburgh, fto., 



ben ii ilium' Our type will be the portable transit-instrument, 



.saving the reader to accommodate what i* here said to the power* of 



hi* own instrument, or to the practice of the OUerratory which he 



adopt* for a model. 



There are three principal part* etpmsand in the out. The iron 

 land, carrying the T with their adjustment* ; the telescope, inserted 

 t right angles through an axis with a small vertical circle for finding 



. ing stars ; and the cross) level The stand U made of cast- 

 ron, and should be of great strength, though perhaps that which is 

 here figured would be found inconveniently heavy if the instrument is 

 often moved. The Y'S are contained in brass pieces, strongly united to 

 the tops of the two uprights. The left hand T has a motion up and 

 down, which U given by a milled screw jortially seen immediately 

 mder the pivot. The right hand v is moved in azimuth by a screw, 

 the milled head of which is seen projected upon the lantern. In inn-t- 

 able instrument* it is very convenient to have this lateral or o/.imutlial 

 adjustment made by screwing against a spring, as it is in this instru- 

 ment. In fixed observatories the adjustment is made by two antago- 

 nist drawing screws, one of which is tightened and the other loosened ; 

 and indeed this is the general construction of instruments of every 

 size, and is the most solid fixture. But it is so convenient to be able 

 to move the instrument at pleasure in azimuth while actually looking 

 through the telescope, that we should strongly recommend the adoption 

 of the counter-spring whenever the instrument is small, and is either 

 M be frequently shifted, or is not furnished with a meridian mark. 

 The spring must press pretty strongly against the screw, and there 

 should be a clamping button in each adjustment, to keep all secure. 



The axis is made of two strong brass cones soldered on the central 

 sphere. The sphere is cast hollow with two shoulders, over which the 

 cones slip. As this is the most important part of the instrument, 

 great care should be taken of the fitting before the axis i* finally put 

 together, and the symmetry of the part* as to the centre should be per- 

 fect. If the instrument is weak here, it is utterly worthless. In the 

 older English instruments the centre was a cube, and that form is fre- 

 quently adopted at present by continental artist*. The transit at 

 Bruxelles, by Oambey, one of the largest and finest instrument* in the 

 world, is so constructed. The essential requisite, however, is $ym- 

 melrical strength, and any i-lrqi' is good which fulfils this condition. 

 The pivots are soldered into the extremities of the cone*, and are 

 turned after the whole is fixed. One of them is pierced to admit light 

 into the axis. In large instruments the pivots have an outer surface 

 of steel, which is lens affected by wear. Greater care is required to 

 guard steel pivot* from rust,* and the turning must be performed with 

 a diamond cutter, as the hard knots to which steel is subject resist and 

 jar the ordinary cutter out of it* place. The pivots should be turned 

 pretty nearly to the same diameter : the marks of the tool are ground 

 off afterwards by collars which are made to fit closely on the pivoto, 

 and are changed and reversed from time to time. When the surface is 

 prrfectly formed, the grinding should be discontinued, as a small 



i*-e of size in the pivots is of little cowequenoe, while an altera- 

 tion of the cylindrical form of the pivots, or of the direction of their 



i line the instrument. The perforated or illitminatnl end of the 

 axis U on the right hand pier in this figure. The light of the lantern 

 shines through this, and lights up an annular plate in the centre, which 

 makes an angle of 45" with the axis and with the telescope, and thus 

 light enough is thrown down to the eye-end to illuminate the field very 

 vividly, while th" opening allows the rays from the object-end to pas* 

 without im|H-diment. The quantity of light may be regulated by a 

 contrivance for iliminUhing the aperture of the lantern, or by a shade 

 passing between the lantern and the pivot. In some transits there U 

 a contrivance for altering the angle of the central reflector in the body 

 of the instrument ; but this, although very handy, is objectionable, as 

 affecting the symmetry of the instrument. In a thirty-inch transit the 

 lantern is within reach, and may be twisted a little, so as to reduce the 

 light at pleasure. The setting circle, with its level and clamp, are 

 towards the illuminated end of the axis. The tail-piece, which is 

 attached to the verniers and level, is held between the rounded ends of 

 the two screws at a. By screwing one and loosening the other, the 

 bubble of the level is brought to the middle, when the vernier points 

 out the reading of the circle. There is a lens and reflector, for lighting 

 and reading off the cirele. The instrument here figured has a \ 

 which reads single minutes ; but the vernier is inconveniently long for 

 a fixed lens, and we should prefer reading to every 2', which is more 

 than sufficiently near for finding or identifying stars. If the small 

 circle i* carefully looked at, two out of three small screws arc seen 

 which fix the circle to the axis. When these are released, the circle 

 will turn freely round. This contrivance will save some trouble when 

 an instrument is used for a long time in the same place without 

 reversing, but is scarcely worth being applied to one which is fre- 

 quently shifted or reversed. The clamp for fixing the telescope in 



Worn the Instrument U smsll and frequently out of o, It obould b 

 removed from the v', snd the pivots protected by caps which slip closely over 

 them. 



