XLII in the nineteenth rank of prerogative instance we will class  supplementary or substitutive instance which we be also wont to call instance  of refuge they be such as supply information where the sense be entire  deficient and we therefore have recourse to they when appropriate instance can  be obtain this substitution be twofold either by approximation or by analogy  for instance there be no know medium which entire prevent the effect of the  magnet in attract iron neither gold nor silver nor stone nor glass wood water  oil cloth or fibrous body air flame or the like yet by accurate experiment a  medium may perhaps be find which will deaden its effect more than another  comparative and in degree as for instance the magnet will not perhaps attract  iron through the same thickness of gold as of air or the same quantity of  ignite as of cold silver and so on for we have not ourselves make the  experiment but it will suffice as a example again there be no know body which  be not susceptible of heat when bring near the fire yet air become warm much  soon than stone these be example of substitution by approximation substitution  by analogy be useful but less sure and therefore to be adopt with some  judgement it serve to reduce that which be not the object of the sense to  their sphere not by the perceptible operation of the imperceptible body but by  the consideration of some similar perceptible body for instance let the  subject for inquiry be the mixture of spirit which be invisible body there  appear to be some relation between body and their source or support now the  source of flame seem to be oil and fat that of air water and watery substance  for flame increase over the exhalation of oil and air over that of water one  must therefore consider the mixture of oil and water which be manifest to the  sense since that of air and flame in general escape the sense but oil and  water mix very imperfect by composition or stir while they be exact and nice  mix in herb blood and the part of animal something similar therefore may take  place in the mixture of flame and air in spirituous substance not bear mixture  very well by simple collision while they appear however to be well mix in the  spirit of plant and animal again if the inquiry do not relate to perfect  mixture of spirit but mere to their composition as whether they easy  incorporate with each other or there be rather as a example certain wind and  exhalation or other spiritual body which do not mix with common air but only  adhere to and float in it in globule and drop and be rather break and pound by  the air than receive into and incorporate with it this can be perceive in  common air and other aeriform substance on account of the rarity of the body  but a image as it be of this process may be conceive in such liquid as  quicksilver oil water and even air when break and dissipate it ascend in small  portion through water and also in the thick kind of smoke last in dust raise  and remain in the air in all of which there be no incorporation and the above  representation in this respect be not a bid one if it be first diligent  investigate whether there can be such a difference of nature between  spirituous substance as between liquid for then these image may convenient be  substitute by analogy and although we have observe of these supplementary  instance that information be to be derive from they when appropriate instance  be want by way of refuge yet we will have it understand that they be also of  great use when the appropriate instance be at hand in order to confirm the  information afford by they of which we will speak more at length when our  subject lead we in due course to the support of induction XLIII in the twenty  rank of prerogative instance we will place lance instance which we be also  wont but for a different reason to call twitch instance we adopt the latter  name because they twitch the understanding and the former because they pierce  nature whence we style they occasional the instance of Democritus they be such  as warn the understanding of the admirable and exquisite subtlety of nature so  that it become rouse and awaken to attention observation and proper inquiry as  for instance that a little drop of ink shall be draw out into so many letter  that silver mere gild on its surface shall be stretch to such a length of gild  wire that a little worm such as you may find on the skin shall possess both a  spirit and a vary conformation of its part that a little saffron shall imbue a  whole tub of water with its colour that a little musk or aroma shall imbue a  much great extent of air with its perfume that a cloud of smoke shall be raise  by a little incense that such accurate difference of sound as articulate word  shall be convey in all direction through the air and even penetrate the poor  of wood and water though they become much weaken that they shall be moreover  reflect and that with such distinctness and velocity that light and colour  shall for such a extent and so rapid pass through solid body such as glass and  water with so great and so exquisite a variety of image and shall be refract  and reflect that the magnet shall attract through every description of body  even the most compact but what be still more wonder that in all these case the  action of one shall not impede that of another in a common medium such as air  and that there shall be bear through the air at the same time so many image of  visible object so many impulse of articulation so many different perfume as of  the violet rise etcetera beside cold and heat and magnetic attraction all of  they I say at once without any impediment from each other as if each have its  path and peculiar passage set apart for it without infringe against or meeting  each other to these lance instance however we be wont not without some  advantage to add those which we call the limit of such instance thus in the  case we have point out one action do not disturb or impede another of a  different nature yet those of a similar nature subdue and extinguish each  other as the light of the sun do that of the candle the sound of a cannon that  of the voice a strong perfume a more delicate one a powerful heat a more  gentle one a plate of iron between the magnet and other iron the effect of the  magnet but the proper place for mention these will be also among the support  of induction XLIV we have now speak of the instance which assist the sense and  which be principal of service as regard information for information begin from  the sense but our whole labour terminate in practice and as the former be the  beginning so be the latter the end of our subject the follow instance  therefore will be those which be chief useful in practice they be comprehend  in two class and be seven in number we call they all by the general name of  practical instance now there be two defect in practice and as many division of  important instance practice be either deceptive or too laborious it be general  deceptive especial after a diligent examination of nature on account of the  power and action of body be ill define and determine now the power and action  of body be define and determine either by space or by time or by the quantity  at a give period or by the predominance of energy and if these four  circumstance be not well and diligent consider the science may indeed be  beautiful in theory but be of no effect in practice we call the four instance  refer to this class mathematical instance and instance of measure practice be  laborious either from the multitude of instrument or the bulk of matter and  substance requisite for any give work those instance therefore be valuable  which either direct practice to that which be of most consequence to mankind  or lessen the number of instrument or of matter to be work upon we assign to  the three instance relate to this class the common name of propitious or  benevolent instance we will now separate discuss these seven instance and  conclude with they that part of our work which relate to the prerogative or  illustrious instance XLV in the twenty first rank of prerogative instance we  will place the instance of the rod or rule which we be also wont to call the  instance of completion or non ultra for the power and motion of body do not  act and take effect through indefinite and accidental but through limit and  certain space and it be of great importance to practice that these shall be  understand and note in every nature which be investigate not only to prevent  deception but to render practice more extensive and efficient for it be  sometime possible to extend these power and bring the distance as it be near  as in the example of telescope many power act and take effect only by actual  touch as in the percussion of body where the one do not remove the other  unless the impel touch the impel body external application in medicine as  ointment and plaster do not exercise their efficacy except when in contact  with the body last the object of touch and taste only strike those sense when  in contact with their organ other power act at a distance though it be very  small of which but few have as yet be note although there be more than man  suspect this happen to take everyday instance when amber or jet attract straw  bubble dissolve bubble some purgative medicine draw humour from above and the  like the magnetic power by which iron and the magnet or two magnet be attract  together act within a definite and narrow sphere but if there be any magnetic  power emanate from the earth a little below its surface and affect the needle  in its polarity it must act at a great distance again if there be any magnetic  force which act by sympathy between the globe of the earth and heavy body or  between that of the moon and the water of the sea as seem most probable from  the particular flood and ebb which occur twice in the month or between the  starry sphere and the planet by which they be summon and raise to their  apogees these must all operate at very great distance again some conflagration  and the kindle of flame take place at very considerable distance with  particular substance as they report of the naphtha of Babylon heat too  insinuate itself at wide distance as do also cold so that the mass of ice  which be break off and float upon the Northern ocean and be bear through the  Atlantic to the coast of Canada become perceptible by the inhabitant and  strike they with cold from a distance perfume also though here there appear to  be always some corporeal emission act at remarkable distance as be experience  by person sail by the coast of Florida or part of Spain where there be whole  wood of lemon orange and other odoriferous plant or rosemary and marjoram bush  and the like last the ray of light and the impression of sound act at  extensive distance yet all these power whether act at a small or great  distance certain act within definite distance which be well ascertain by  nature so that there be a limit depend either on the mass or quantity of the  body the vigour or faintness of the power or the favourable or impede nature  of the medium all of which shall be take into account and observe we must also  note the boundary of violent motion such as missile projectile wheel and the  like since they be also manifest confine to certain limit some motion and  virtue be to be find of a direct contrary nature to these which act in contact  but not at a distance namely such as operate at a distance and not in contact  and again act with less force at a less distance and the reverse sight for  instance be not easy effective in contact but require a medium and distance  although I remember have hear from a person deserve of credit that in be cure  of a cataract which be do by put a small silver needle within the first coat  of the eye to remove the thin pellicle of the cataract and force it into a  corner of the eye he have distinct see the needle move across the pupil still  though this may be true it be clear that large body can be see well or  distinct unless at the vertex of a cone where the ray from the object meet at  some distance from the eye in old person the eye see better if the object be  move a little further and not near again it be certain that in projectile the  impact be not so violent at too short a distance as a little afterward such be  the observation to be make on the measure of motion as regard distance there  be another measure of motion in space which must not be pass over not relate  to progressive but spherical motion that be the expansion of body into a great  or their contraction into a lesser sphere for in our measure of this motion we  must inquire what degree of compression or extension body easy and ready admit  of accord to their nature and at what point they begin to resist it so as at  last to bear it no further as when a inflate bladder be compress it allow a  certain compression of the air but if this be increase the air do not suffer  it and the bladder be burst we have prove this by a more delicate experiment  we take a metal bell of a light and thin sort such as be use for salt cellar  and immerse it in a basin of water so as to carry the air contain in its  interior down with it to the bottom of the basin we have first however place a  small globe at the bottom of the basin over which we place the bell the result  be that if the globe be small compare with the interior of the bell the air  will contract itself and be compress without be force out but if it be too  large for the air ready to yield to it the latter become impatient of the  pressure raise the bell partly up and ascend in bubble to prove also the  extension as well as the compression which air admit of we adopt the follow  method:--We take a glass egg with a small hold at one end we draw out the air  by violent suction at this hold and then close the hold with the finger  immerse the egg in water and then remove the finger the air be constrain by  the effort make in suction and dilate beyond its natural state and therefore  strive to recover and contract itself so that if the egg have not be immerse  in water it will have draw in the air with a hiss sound now draw in a  sufficient quantity of water to allow the air to recover its former dimension  it be well ascertain that rare body such as air admit of considerable  contraction as have be before observe but tangible body such as water admit of  it much less ready and to a less extent we investigate the latter point by the  follow experiment we have a leaden globe make capable of contain about two  pint wine measure and of tolerable thickness so as to support considerable  pressure we pour water into it through a aperture which we afterward close  with melt lead as soon as the globe be fill with water so that the whole  become perfect solid we next flatten the two opposite side with a heavy hammer  which necessary cause the water to occupy a less space since the sphere be the  solid of great content and when hammer fail from the resistance of the water  we make use of a mill or press till at last the water refuse to submit to a  great pressure exude like a fine due through the solid lead we then compute  the extent to which the original space have be reduce and conclude that water  admit such a degree of compression when constrain by great violence the more  solid dry or compact body such as stone wood and metal admit of much less and  indeed scarce any perceptible compression or expansion but escape by break  slip forward or other effort as appear in bend wood or steel for watch spring  in projectile hammer and many other motion all of which together with their  degree be to be observe and examine in the investigation of nature either to a  certainty or by estimation or comparison as opportunity permit XLVI in the  twenty second rank of prerogative instance we will place the instance of the  course which we be also wont to call water instance borrow our expression from  the water hour glass employ by the ancient instead of those with sand they be  such as measure nature by the moment of time as the last instance do by the  degree of space for all motion or natural action take place in time more or  less rapid but still in determine moment well ascertain by nature Even those  action which appear to take effect sudden and in the twinkle of a eye as we  express it be find to admit of great or less rapidity in the first place then  we see that the return of the heavenly body to the same place take place in  regular time as do the flood and ebb of the sea the descent of heavy body  towards the earth and the ascent of light body towards the heavenly sphere  take place in definite time accord to the nature of the body and of the medium  through which it move the sail of ship the motion of animal the transmission  of projectile all take place in time the sum of which can be compute with  regard to heat we see that boy in winter bath their hand in the flame without  be burn and conjurer by quick and regular movement overturn vessel fill with  wine or water and replace they without spill the liquid with several similar  instance the compression expansion and eruption of several body take place  more or less rapid accord to the nature of the body and its motion but still  in definite moment in the explosion of several cannon at once which be  sometime hear at the distance of thirty mile the sound of those near to the  spot be hear before that of the most distant Even in sight who action be most  rapid it be clear that a definite time be necessary for its exertion which be  prove by certain object be invisible from the velocity of their motion such as  a musket ball for the flight of the ball be too swift to allow a impression of  its figure to be convey to the sight this last instance and other of a like  nature have sometime excite in we a most marvellous doubt no less than whether  the image of the sky and star be perceive as at the actual moment of its  existence or rather a little after and whether there be not with regard to the  visible appearance of the heavenly body a true and apparent time as well as a  true and apparent place which be observe by astronomer in parallaxes it appear  so incredible to we that the image or radiation of heavenly body can sudden be  convey through such immense space to the sight and it seem that they ought  rather to be transmit in a definite time that doubt however as far as regard  any great difference between the true and apparent time be subsequent complete  set at rest when we consider the infinite loss and diminution of size as  regard the real and apparent magnitude of a star occasion by its distance and  at the same time observe at how great a distance at least sixty mile body  which be mere white can be sudden see by we for there be no doubt that the  light of the heavenly body not only far surpass the vivid appearance of white  but even the light of any flame with which we be acquaint in the vigour of its  radiation the immense velocity of the body themselves which be perceive in  their diurnal motion and have so astonish think man that they have be more  ready to believe in the motion of the earth render the motion of radiation  from they marvellous as it be in its rapidity more worthy of belief that which  have weigh most with we however be that if there be any considerable interval  of time between the reality and the appearance the image will often be  interrupt and confuse by cloud from in the meantime and similar disturbance of  the medium let this suffice with regard to the simple measure of time it be  not mere the absolute but still more the relative measure of motion and action  which must be inquire into for this latter be of great use and application we  perceive that the flame of firearms be see soon than the sound be hear  although the ball must have strike the air before the flame which be behind it  can escape the reason of which be that light move with great velocity than  sound we perceive also that visible image be receive by the sight with great  rapidity than they be dismiss and for this reason a violin string touch with  the finger appear double or triple because the new image be receive before the  former one be dismiss hence also ring when spin appear globular and a light  torch bear rapid along at night appear to have a tail upon the principle of  the inequality of motion also Galileo attempt a explanation of the flood and  ebb of the sea suppose the earth to move rapid and the water slow by which  mean the water after accumulate will at interval fall back as be show in a  vessel of water make to move rapid he have however imagine this on data which  can be grant namely the earth motion and beside do not satisfactory account  for the tide take place every six hour a example of our present point the  relative measure of motion and at the same time of its remarkable use of which  we have speak be conspicuous in i fill with gunpowder where immense weight of  earth building and the like be overthrow and prostrate by a small quantity of  powder the reason of which be decide this that the motion of the expansion of  the gunpowder be much more rapid than that of gravity which will resist it so  that the former have terminate before the latter have commence hence also in  missile a strong blow will not carry they so far as a sharp and rapid one nor  can a small portion of animal spirit in animal especial in such vast body as  those of the whale and elephant have ever bend or direct such a mass of body  be it not owe to the velocity of the former and the slowness of the latter in  resist its motion in short this point be one of the principal foundation of  the magic experiment of which we shall present speak where a small mass of  matter overcome and regulate a much large if there but be a anticipation of  motion by the velocity of one before the other be prepare to act final the  point of the first and last shall be observe in all natural action thus in a  infusion of rhubarb the purgative property be first extract and then the  astringent we have experience something of the same kind in steep violet in  vinegar which first extract the sweet and delicate odour of the flower and  then the more earthy part which disturb the perfume so that if the violet be  steep a whole day a much faint perfume be extract than if they be steep for a  quarter of a hour only and then take out and since the odoriferous spirit in  the violet be not abundant let other and fresh violet be steep in the vinegar  every quarter of a hour as many as six time when the infusion become so  strengthen that although the violet have not altogether remain there for more  than one hour and a half there remain a most please perfume not inferior to  the flower itself for a whole year it must be observe however that the perfume  do not acquire its full strength till about a month after the infusion in the  distillation of aromatic plant macerate in spirit of wine it be well know that  a aqueous and useless phlegm rise first then water contain more of the spirit  and last water contain more of the aroma and many observation of the like kind  well worthy of notice be to be make in distillation but let these suffice as  example XLVII in the twenty three rank of prerogative instance we will place  instance of quantity which we be also wont to call the dose of nature borrow a  word from medicine they be such as measure the power by the quantity of body  and point out the effect of the quantity in the degree of power and in the  first place some power only subsist in the universal quantity or such as bear  a relation to the confirmation and fabric of the universe thus the earth be  fix its part fall the water in the sea flow and ebb but not in the river  except by the admission of the sea then again almost all particular power act  accord to the great or less quantity of the body large mass of water be not  easy render foul small be new wine and beer become ripe and drinkable in small  skin much more ready than in large cask if a herb be place in a considerable  quantity of liquid infusion take place rather than impregnation if in less the  reverse a bath therefore and a light sprinkle produce different effect on the  human body light due again never fall but be dissipate and incorporate with  the air thus we see that in breathe on gem the slight quantity of moisture  like a small cloud in the air be immediate dissolve again a piece of the same  magnet do not attract so much iron as the whole magnet do there be some power  where the smallness of the quantity be of more avail as in boar a sharp point  pierce more ready than a blunt one the diamond when point make a impression on  glass and the like here too we must not rest content with a vague result but  inquire into the exact proportion of quantity requisite for a particular  exertion of power for one will be apt to suppose that the power bear a exact  proportion to the quantity that if a leaden bullet of one ounce for instance  will fall in a give time one of two ounce ought to fall twice as rapid which  be most erroneous nor do the same ratio prevail in every kind of power their  difference be considerable the measure therefore must be determine by  experiment and not by probability or conjecture last we must in all our  investigation of nature observe what quantity or dose of the body be requisite  for a give effect and must at the same time be guard against estimate it at  too much or too little