### In this lecture, we’ll study key tools artists use to arrive at correct proportions. In particular, learn how to use an analog clock face as a way to quantify angles, how to use a standard unit of measure to measure across the picture plane, and how to use level and plumb lines. Then put these elements together in practice.

**Tools for Accurate Proportion and Measurement**

The tools for accurate proportion that we’ve already discussed include the following:

- Centerline, a type of construction line that helps establish an object’s placement within the drawing and helps maintain the subject’s direction. The centerline also serves as an aid in drawing shapes proportionately in relation to the object’s center.
- Constituent or building-block shapes, which help relate both the left and right sides and the width-to-height proportions of an object or part of an object.
- Large ground shapes, which set up proportions for the whole drawing.

Aggregate shape, or the simple shape that contains the subject and captures the height-to-width proportion. Using ground and aggregate shapes together defines and helps control the overall proportions in a drawing. - Eyeballing, that is, looking at the shape you’ve drawn and asking yourself if it corresponds to what you’re seeing.
- Negative shape, which we tend to see more accurately than positive shapes because we have no preconceptions about what they look like. This allows us to see them in a purely visual and analytic manner. Taken together, a group of negative shapes will reveal the silhouette of an object in accurate proportion.

The first exercise in this lecture is to make a drawing of a box similar to the one shown below. Follow the steps outlined, concentrating on the large ground shapes and negative shapes, as well as the other tools we’ve discussed so far. As a second exercise, see how you can apply the grid to the box drawing.

**Determining Angles with the Clock-Hand Method**

Our next tool represents a means for quantifying tricky angles. To understand the idea behind the clock-hand method, hold a pencil out in front of you with your left hand, vertically, point up. Closing one eye, rotate the pencil so that it comes into line with the angle of the box. Then, take a second pencil in your right hand and place it pointing straight up from the eraser end of the first pencil.

Now, imagine that the pencils are hands on an analog clock face, and tell the time. Here, we have about 13 minutes to noon. This method represents a way to quantify and remember an angle.

We just read this angle as an acute one, but we could equally read it as obtuse. Depending on whether you’re right-handed or left handed, one way or the other may be more comfortable.

Once you’ve practiced this method a couple of times, you can imagine the hour hand, and you’ll need only a single hand and pencil to measure the angle. The most important thing to remember here is to hold your pencil parallel to an imaginary picture plane, as if it were held against a glass plane perpendicular to the floor. You don’t want to tip your pencil into space.

**A Standard Unit of Measure**

We’ve all seen images of an artist, standing in front of an easel, holding out his arm, closing one eye, and looking out over his thumb. This is a version of another tool we can use to create accurate proportions: a standard unit of measure. Here, you identify some part of what you’re seeing to be used to measure everything else. In choosing the unit of measure, there are two factors to keep in mind: its orientation and its scale. Regarding orientation, you want something that is parallel to the picture plane, not anything that recedes into space. In fact, it’s best if what you choose is a self-contained unit and is vertical or horizontal. Regarding scale, the unit you choose can’t be too big or too small.

In the case of the box, the front edge may be a good choice. Although it’s a couple degrees off true vertical, it will work for the purposes of this drawing. Hold a well-pointed pencil vertically, with the point up. With one eye closed, outstretch your arm fully, and align the pencil’s tip with the top of the standard unit of measure. With your thumb and first finger, hold the pencil at the base of the standard unit. This allows you to capture the unit on your pencil, which you can then use to measure across the picture plane.

**Level Lines and Plumb Lines**

Yet another tool is either a horizontal level line or a vertical plumb line. Turn your pencil horizontally and line it up with any point, say, the far left inside corner of the box. Then, look to see if anything to the right lines up with it. In this case, there doesn’t seem to be perfect alignment, but we can tell that the far right inside corner is just a bit higher than the left.

Of course, you can also use this technique vertically to create a plumb line. Both tools—the level line or the plumb line—can be used to see how things line up and to understand how different points or edges correlate.

With these new tools—clock hands for angles, a standard unit of measure, and level and plumb lines to locate positions—make a second drawing of the box. At first, you should follow the instructions for using these tools as you would a recipe, but once you’ve worked with them for a period of time, you’ll find yourself using them in a much more fluid, organic way. Our method here is to break down the processes into understandable pieces, but as you use them, they’ll become natural, embedded in the way you scan everything you see.

**Sighting the Half**

Related to some of the tools we’ve studied is an approach called sighting the half. This is another method to help you imagine an even grid over your subject and measure through your drawing. You’ll then find the key points that help you draw proportionately.

**Drawing as an Interrogative Process**

As you’re beginning to realize, drawing can be an interrogative process. We ask one question after another: How does the picture plane divide? What’s the largest shape? What’s the angle of that diagonal? How long is it? A drawing can represent the sum of an artist’s responses to these questions.

**From the lecture series How to Draw**

Taught by Professor David Brody

Taught by Professor David Brody