Use of “by” to indicate means

Question

The preposition of “by” is used to indicate how something is done as in: “We are going to travel by car” and “He made history by becoming the first man to sail around the world.”

Now, how about sentences like:

(1) “The image of the particles was taken by an electron microscope.”

or

(2) “The absorption curve was measured by a spectrometer.”

I was told in school that "by" cannot be used to indicate a tool with which you perform some activity and would personally use “with” for the first sentence and “on” for the second but I see people write sentences like these all the time and am not so sure any more.

Can anybody shed light on this issue? Would you say sentences (1) and (2) are acceptable?

Answer 1

It would not be appropriate to use by if you referred to the scientist who used the tool, e.g. this would be wrong:

The scientist took an image of the particles by an electron microscope.

You would instead use with or using. by could be used to refer to the scientist, e.g.

An image of the particles was taken by the scientist using an electron microscope.

But in the sentence you gave, the microscope is the agent, not a tool, and by is used to refer to an agent. This is anthropomorphising the microscope somewhat. You could also write it in the active voice as:

The electron microscope took an image of the particles.

The difference between these ways of describing the action is whether you want to emphasize the human actor (the scientist) or the device that was employed.

Answer 2

It's interesting to note the difference between "by car" and "with a car".

What's probably more interesting to note is that both your example sentences are passive. In a passive sentence, the agent is usually introduced with by:

The dog was kicked by the man.
The exam was corrected by the teacher.

That means that in your sentences, the electron microscope took the picture, and the spectrometer measured the absorption curve.

Now some people will argue that it is indeed the camera that takes the picture, but we usually think of the picture being taken by the photographer, with a camera.

The fact that you see people write sentences like this is not very strange. Language is constantly changing, and it may well be that the semantic distinction between "I took the picture with my camera" and "my camera took the picture" is not one that is important enough for some people to bother with.

Answer 3

As so many other prepositions "by" has a lot of special uses.

by + gerund

It indicates the way/method/manner how something is done:
She earns her living by selling insurance.

by + vehicle

e.g. to travel by car. This is "to travel by using the car" with the gerund omitted. So this is only a special case of by + gerund

by + passive agent

The novel Tarzan of the Apes was written by Edgar Rice Burroughs.

Tools are no passive agent. So "with + tool" or "by means of + tool" or even "using + tool" are better. Sure you can find instances where "by + tool" is used. This only shows that the use of prepositions is difficult and not everybody uses them in the proper way. Or as Oerkelens said some people don't care to differentiate between passive agent and tool.