Introduction

The first conversation of the book is a simple one that introduces us to the participants. It sets the scene as to the way things are going to be discussed in the rest of the volume and how the Author will instruct his students.

MECHANICS

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CONVERSATION I.

INTRODUCTION

FATHER — CHARLES — EMMA

CHARLES. Father, you told sister Emma and me, that, after we had finished reading "Evenings at Home," you would explain to us some of the principles of natural philosophy : will you begin in the morning ?
  Father. Yes, I am quite at leisure ; and I shall, indeed, at all times take a delight in communicating to you the elements of useful knowledge ; and the more so in proportion to the desire which you have of collecting and storing those facts that may enable you to understand the operations of nature, as well as the works of ingenious artists. These, I trust, will lead you insensibly to admire the wisdom and goodness by means of which the whole system of the universe is constructed and supported.
  Emma. But can philosophy be comprehended by children so young as we are? I thought that it had been the business of men, and of old men too.
  F. Philosophy is a word which, in its original sense, signifies only a love or desire of wisdom ; and you will not allow that you and you brother are too young to wish for knowledge.
  E. So far from it, that the more knowledge I get the better I seem to like it ; and the number of new ideas which, with a little of your assistance, I have obtained the "Evenings at Home," and the great pleasure which I have received from the perusal of that work, will, I am sure, excite me to read it again and again.
  F. You will find very little, in the introductory parts of natural and experimental philosophy, that will require more of your attention than many parts of that work with which you were so delighted.
  C. But in some books of natural philosophy, which I have occasionally looked into, a number of new and uncommon words have perplexed me ; I have also seen references to figures, by means of large letters and small, the use of which I did not comprehend.
  F. It is frequently a dangerous practice for young minds to dip into subjects before they are prepared, by some previous knowledge, to enter upon them ; since it may create a distaste for the most interesting topics. Thus, those books which you now read with so much pleasure would not have afforded you the smallest entertainment a few years ago, when you must have spelt out almost every word in each page. The same sort of disgust will naturally be felt by persons who should attempt to read works of science before the leading terms are explained and understood. The word angle is continually recurring in subjects of this sort ; do you know what an angle is ?
  E. I do not think I do : will you explain what it means ?
  F. An angle is made by the opening of two straight * lines. In this figure there are two straight lines ab and cb meeting at point b, and the opening made by them is called an angle.
  C. Whether that opening be small or great, is it still called an angle ?
  F. It is ; your drawing compasses may familiarize to your mind the idea of an angle ; the lines in this figure will aptly represent the legs of the compasses, and the point b the joint upon which they move or turn. Now you may open the legs to any distance you please, even so far that they shall form one straight line ; in that position only they do not form an angle. In every other situation an angle is made by the opening of these legs, and the angle is said to be greater or less, as that opening is greater or less. An angle is another word for a corner.
  E. Are not some angles called right angles ?
  F. Angles are either right, acute or  obtuse. When the line ab meets another line cd in such a manner as to make the angles abd and abc equal to one another, then those angles are called right angles. And the line ab is said to be perpendicular to cd. Hence to be perpendicular to, or to make right angles with, a line, means one and the same thing.
  C. Does it signify how you call the letters of an angle ?
  F. It is usual to call every angle by three letters, and that at the angular point must always be the middle letter of the three. There are cases, however, where an angle may be denominated by a single letter ; thus the angle abc may be called simply the angle b, for there is no danger of mistake, because there is but a single angle at the point b.
  C. I understand this ; for if, in the second figure, I were to describe the angle by the letter b only, you would not know whether I meant the angle abc or abd.
  F. That is the precise reason why it is necessary, in most descriptions, to make use of three letters. An acute angle (Fig. 1, abc) is less than a right angle ; and and obtuse angle (Fig. 3, abc) is greater than a right angle.
  E. You see the reason now, Charles, why letters are placed against or by figures, which puzzled you before.
  C. I do ; they are intended to distinguish the separate parts of each, in order to render the description of them easier both to the author and the reader.
  E. What is the difference, papa, between an angle and a triangle ?
  F. An angle being made by the opening of two lines and as you know that two straight lines cannot enclose a space, so a triangle abc is a space bounded by three straight lines. It takes its name from the property of containing three angles. There are various sorts of triangles, but it is not necessary to enter upon these particulars, as I do not wish to burden your memories with more technical terms than we have occasion for.
  C. A triangle, then, is a space or figure containing three angles, and bounded by as many straight lines.
  F. Yes, that description will answer our present purpose.

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* Straight lines, in works of science are usually denominated right lines.

Here are Father, Charles and Emma then. To me, Father starts off sounding a little pompous and patronising. This is probably because this has been set up as an intimate conversation between an adult and his children, yet it is quite obviously being played for the audience and he's over-acting. We are familiar with this sort of staged reality in the present day; producers of current semi-fictional pieces are much more adept at natural dialogue than this is. It flows more freely in my head if I imagine it to be a stage production where Father's exaggerated earnestness comes across more as exaggerated characterisation rather than clunky exposition. This also allows me to imagine Charles and Emma pulling funny faces at the audience when papa is being tiresome; which makes me smile.

Given my previous misgivings regarding possible gender bias in the book, I'm pleased that it is Emma who brings up that philosophy is seen as "the business of men, and of old men too". Even though the response only addresses the age of students, I'd like to think that the fact a young girl asks the question shows a level of awareness and concern in the author concerning the education of women.

From this short exchange, Charles and Emma seem to be fairly indistinguishable from each other. It's possible that it was felt to be a "good thing" to have both a boy and a girl to appeal to the widest range of potential readers. What I'd really like is if they prove to have vastly different aptitudes; maybe Charles is a complete idiot at anything mathematical and Emma can't get her head round steam engines. Somehow I doubt it though. I imagine Father will turn out to be an exemplary teacher, while both Charles and Emma will be the swottiest of teacher's pets. Gold stars for everyone!

The book which the children had previously been enjoying, Evenings at Home, was a book of children's stories written in the 1790s which appears to have remained popular throughout the 19th century. It was authored by Anna Laetitia Barbauld and her brother Dr. John Aikin. Barbauld was a teacher and children's author at a time when female writers were exceedingly uncommon; her primers laid the ground for many educational volumes, these Scientific Dialogues would appear to be among their number. Evenings at Home is by no means the earliest example of children's literature, but the form was still very rare at this time.

Father looks to have done a good job explaining the concept of angles. I seem to remember my introduction to them being fairly similar. Having said that, I initially bridled at the assertion that 180 degrees was not an angle; to me angles have long since simply become a number between 0 and 360 (or more commonly 6.283). This is down to the extent of my learning and use of angles over the years, which far surpasses that of your average pre-teen.

The only observation I have regarding the triangles passage is to point out how extra-ordinarily short it is. It hardly seems worth having brought it up at all if all you're going to say is "this is a triangle, it has three angles". I think it says more about me than the author that I was looking forward to a discourse about the properties of a nice pointy isosceles triangle or maybe an elegant 3-4-5 right triangle.

The funniest thing in the dialogue appears during the attempt to explain notations on diagrammatic figures. Charles notes that he has repeatedly found technical notations confusing. Father presents Figure 1 to clear everything up. The only problem with this is that he's got it all upside-down. A slightly embarrassing start for the learned gentleman there!

The only bit of technical stuff here that I have never come across is straight lines being referred to as "right lines". In fact, a quick unscientific look at Wikipedia page reveals that the word right is not used in any sense on the page Line (geometry). [Not that you should trust Wikipedia without checking references.]


Next up, the divisibility of matter. I'm guessing we're not jumping straight into nuclear fission; that would be more than a little odd, not to mention massively anachronistic.

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