网络如何连接

浏览器生成消息

生成HTTP请求消息

URL：浏览器是具有多种客户端功能的综合性客户端软件，因此它需要一些东西判断应该使用其中那种功能来访问相应的数据，而不同的URL就是用来干这个的

1
2
3
4
5
6
7
8
9
10
11

http://user:password@www.glasscom.com:80/dir/file1.htm

ftp://user:password@ftp.glasscom.com:21/dir/file1.htm

file://localhost/c:/path/file1.zip

mailto:tone@glasscom.com

news:comp.protocols.tcp-ip

尽管 URL 有各种不同的写法，但它们有一个共同点，那就是 URL 开头的文字，即“http:”“ftp:”“file:”“mailto:”这部分文字都表示浏览器应当使用的访问方法

IMAGINARY NUMBERS (continued)

THE DEFINITION of the multiplication of ordered couples is guided by exactly the same considerations as is that of their addition. The interpretation of multiplication must be such that

有序对的乘法定义完全遵循与其加法相同的原则。乘法的解释必须满足以下条件：

IMAGINARY NUMBERS

IF THE mathematical ideas dealt with in the last chapter have been a popular success, those of the present chapter have excited almost as much general attention. But their success has been of a different character, it has been what the French term a succes de scandale. Not only the practical man, but also men of letters and philosophers have expressed their bewilderment at the devotion of mathematicians to mysterious entities which by their very name are confessed to be imaginary. At this point it may be useful to observe that a certain type of intellect is always worrying itself and others by discussion as to the applicability of technical terms. Are the incommensurable numbers properly called numbers? are the positive and negative numbers really numbers? are the imaginary numbers imaginary, and are they numbers?— are types of such futile questions. Now it cannot be too clearly understood that, in science, technical terms are names arbitrarily assigned, like Christian names to children. There can be no question of the names being right or wrong. They may be judicious or injudicious; for they can sometimes be so arranged as to be easy to remember, or so as to suggest relevant and important ideas. But the essential principle involved was quite clearly enunciated in Wonderland to Alice by Humpty Dumpty, when he told her, apropos of his use of words, 'I pay them extra and make them mean what I like.' So we will not bother as to whether imaginary numbers are imaginary, or as to whether they are numbers, but will take the phrase as the arbitrary name of a certain mathematical idea, which we will now endeavour to make plain.

GEBERALIZATIONS OF NUMBER

ONE GREAT peculiarity of mathematics is the set of allied ideas which have been invented in connexion with the integral numbers from which we started. These ideas may be called extensions or generalizations of number. In the first place there is the idea of fractions. The earliest treatise on arithmetic which we possess was written by an Egyptian priest, named Ahmes, between 1700 B.C. and 1000 B.C. , and it is probably a copy of a much older work. It deals largely with the properties of fractions. It appears, therefore, that this concept was developed very early in the history of mathematics. Indeed the subject is a very obvious one. To divide a field into three equal parts, and to take two of the parts, must be a type of operation which had often occurred. Accordingly, we need not be surprised that the men of remote civilizations were familiar with the idea of two-thirds, and with allied notions. Thus as the first generalization of number we place the concept of fractions. The Greek thought of this subject rather in the form of ratio, so that a Greek would naturally say that a line of two feet in length bears to line of three feet in length the ratio of 2 to 3. Under the influence of our algebraic notation we would more often say that one line was two-thirds of the other in length, and would think of two-thirds as a numerical multiplier.

THE SYMBOLISM OF MATHEMATICS

WE NOW return to pure mathematics, and consider more closely the apparatus of ideas out of which the science is built. Our first concern is with the symbolism of the science, and we start with the simplest and universally known symbols, namely, those of arithmetic.

我们现在回到纯数学，仔细考虑构建这一科学的思想工具。我们首先关注的是该科学的符号系统，我们从最简单且普遍知晓的符号开始，即算术符号。

Dynamics

THE WORLD had to wait for eighteen hundred years till the Greek mathematical physicists found successors. In the sixteenth and seventeenth centuries of our era great Italians, in particular Leonardo da Vinci, the artist (bron 1452, died 1519), and Galileo (bron 1564,died 1642), rediscovered the secret, known to Archimedes, of relating abstract mathematical ideas with the experimental investigation of natural phenomena. Meanwhile the slow advance of mathematics and the accumulation of accurate astronomical knowledge had placed natural philosophers in a much more advantageous position for research. Also the very egoistic self-assertion of that age, its greediness for personal experience, led its thinkers to want to see for themselves what happened; and the secret of the relation of mathematical theory and experiment in inductive reasoning was practically discovered. It was an act eminently characteristic of the age that Galileo, a philosopher , should have dropped the weights from the leaning tower of Pisa. There are always men of thought and men of action; mathematical physics is the product of an age which combined in the same men impulses to thought with impulses to action.

METHODS OF APPLICATION

THR WAY in which the idea of variables satisfying[ˈsætɪsfaɪɪŋ] a relation occurs in the applications of mathematics is worth thought, and by devoting[ dɪˈvoʊt] some time to it we shall clear up our thoughts on the whole subject.

变量满足关系的概念在数学的应用中出现的方式值得思考，通过花一些时间来研究，我们将能够澄清对整个主题的思路。

变量 Variables[ ˈverɪəbl]

数学作为一门科学起源于某人（可能是希腊人）首次证明了关于某些事物（something）或任何事物（anything）的命题，而这些命题并不需要具体指定某个确定的事物。这些命题最初是由希腊人提出并应用于几何学，因此，几何学成为了古希腊的重要数学科学。在几何学兴起后的几个世纪里，尽管一些后来的希腊数学家对代数有一些初步的认识，但代数直到很久之后才真正开始起步。

数学的本质

数学的学习往往以失望开始。这门科学的重要应用、其思想的理论兴趣以及其方法的逻辑严谨，都引发了对迅速接触有趣过程的期望。我们被告知，借助它的帮助，我们可以衡量星星的重量，数出一滴水中数十亿的分子。然而，像哈姆雷特父亲的幽灵一样，当我们试图用思维去理解它时，这门伟大的科学成功逃避了——‘它在这里’，‘它在那里’，‘它又消失了’——，而我们所看到的并没有像幽灵那样飘忽不定，不能让我们认为它过于崇高，超出了我们粗浅方法的理解。在某些情况下，这种幽灵般的表现，可能就出现在那些占据初等数学著作页面的琐碎结果中。

为大家推荐的是一本寓言小说——《动物农场》。由英国作家乔治·奥威尔所写，于1945年出版。

这本小说给我带来深深的冲击和震撼，然而让我很遗憾的是，我能读到这本书确实是太晚了!在序言中，译者傅惟慈先生写到，该书直到2003年在上海文艺出版社重新印行《1984》时，才与之作为合集一并允许出版。

《动物农场》能与广大普通大众见面实在太难了，也许是因为它作为寓言故事太通俗了，太容易使人们回想起曾经有一段不愉快的历史，其中的某些故事角色促使人们不由自主地联想到真实的历史人物，但这小说却是作者在1943年动笔的……

为我所能读到时，已相隔70多年……