Preface
Late at night, 1997, in some little one-bedroom apartment on Lexington Avenue, in Lexington, Kentucky, I installed my very rst 3D so ware on my self-built HP Windows 95 workstation. It had 64 megabytes of RAM and an Intel Pentium 32 gigahertz processor. Caligari Truespace was an ancient VRML (Virtual Reality Markup Language) authoring soware that I had downloaded for free. It was my very rst experience with 3D graphics.
I had seen it in movies. I had seen it in video games. But I had never really held the tools of creation in my hands and manipulated objects in 3D space before. I eagerly navigated around the interface of the default scene le, which was strewn with various old-timey 3D objects: a teapot, a house, a spider, and a roller coaster. I selected the spider and chose the “rotate” tool, and for the very rst time in my life, I manipulated a model in three dimensions on a computer screen.
ere was no going back. From that one particular moment in time and space, a light went on in my head and I was obsessed. I could not stop thinking about 3D animation. e possibilities exploded. e next 14 years of my life would be a single-minded drive down that same road, without ever stopping to wonder if I was on the right path. 3D graphics were my passion and aspiration. And although that path was ultimately successful, I had a long way to go in terms of my basic understanding.
Here is the problem: I had no idea what I was doing. I didn’t know a damn thing about 3D graphics. I didn’t know what a vertex was, I didn’t know how materials and lights worked, and I didn’t know the di erence between Euler and Quaternion rotations or how to edit tangents in a motion graph. I knew, essentially, bupkiss. I bought books, but they were so technical that I had no idea what they were saying. I was not a stupid person. But even a smart person cannot learn 30 years of computer graphics by reading a technical manual on VRML speci cations. In 1997,
there were no Art Institutes, no ITT classes, and no university courses that could make any sense of all this new stu I was being exposed to. ere was no YouTube. ere was no Google. ere was no resource for a guy like me.
So, I taught myself. But in doing so, I tried to create 3D animations and e ects without having any idea exactly how to do it. I didn’t know the basics. I just wanted to make something “cool.” But when you try to make art without knowing how to paint, you don’t usually do a very good job.
I began to learn things from experience—my rst jobs, my rst work with other 3D artists who showed me a few things. I learned how to do speci c jobs on speci c so ware, but my general understanding of how all this stu “worked” was vague and sketchy. When you learn to use speci c so ware to do speci c things, you can do a good job, but you end up a lot like a trained monkey. You can push buttons in a sequence without really knowing what they are for. I wanted more than that.
Time went on, and my skills and understanding grew. I was working full time by then for Red Zone, a game developer for Playstation (which was eventually bought by Sony Computer Entertainment America). I learned some new things, new skills, and new speci cs. We ran into problems with things, and the solutions to those problems made sense in various ways, but despite my skills and technical expertise that grew as a result of my daily involvement with games and game development, I was still lacking a fundamental understanding of the mechanics going on under the hood. I could drive the car, but I had no idea how the engine worked! A great racecar driver can succeed without ever peeking under the hood, but if the car breaks down he or she will be stranded.
e years went on, and my knowledge was constantly and exponentially increased by the daily grind and repetition of various problems that occur in modeling, rendering, and animation. I knew how to x all kinds of problems, but I had never learned certain basic elements of 3D graphics. Fast forward several years, a er my exit from my career as a game developer and the beginning of my academic career. My master’s degree was in instructional design, which I had never thought I would use again, but I was asked to create a curriculum for learning the “basics” of 3D graphics. As I started work on this curriculum, I realized that there was a lot of stu I still didn’t know! Luckily, with my 14 years of experience as a modeler, animator, and rigger, I knew enough to piece together what I didn’t know. As I transitioned into the role of a professor, I began teaching
these essential skills and knowledge blocks, and tweaking them as I saw how people learned and reconstructed my lessons on their own.
e result is this book, which I have thoughtfully constructed to give the complete novice and even the experienced artist a basic foundational understanding of all things that make up the core of 3D computer graphics, written for the non-technical mind. It is written to impart everything you need to know about 3D graphics, without being tied to an individual piece of so ware. While the examples are speci cally taken from Autodesk Maya, they rarely mention anything tied to the speci c soware tools (the most notable exception is in the Rendering and Materials section), but instead focus on the common elements of all 3D graphics and how they work.
As you go through this book, keep in mind that this stu isn’t simple— in fact, it is extremely complex. is book is intended to distill that complexity and focus on only the essential skills and knowledge that you will need to start your path down the road to becoming a skilled 3D artist. Good luck! It is not a quick path. My best advice is to learn the basics, gather your skills in what suits you the best, and focus on that one thing.
Additional material is available from the CRC Web site: http://www. crcpress.com/product/ISBN/9781482224122.
Understanding 3D Space
HOW DO WE KNOW WHERE THINGS ARE IN 3D GRAPHICS?
Cartesian Mapping and 3D Coordinates
If I asked you, “Where is the Earth?” what would you say?
You might say, “In relation to what?” e sun? Mars? Anywhere? Nowhere? is might start to sound like an exercise in philosophy, but the point I am trying to make is that location is relative. We know where things are because we can measure them against various reference points (which can be as simple as our own position).
In the real world, we don’t have any nite points in space where we can measure things from—we simply create a relative idea of position by measuring it from another point. Imagine, for instance, we had a duplicate of ourselves somewhere on Mars. Let us also assume that Earth and Mars were not moving at all. How would we know where our doppelganger was, relative to where we were? We could stretch an imaginary tape measure between us, and then we could get an exact distance. We can measure all things from our precise position and get an idea of where the Martian version of us is, relative to where we are, as shown in Figure 1.1.
HOW DO WE DETERMINE THESE POSITIONS?
The Grid
Much like this method of locating things, the world of 3D graphics depends on a giant “grid” or location coordinate system, to exist. e 3D grid is an extension of our method of measuring distance; essentially, it is
FIGURE 1.1 You and your Martian clone with a line drawn between you—it is easy to calculate distance when you are not in motion!
a giant graph that encompasses the entirety of the 3D world. is grid is known as Cartesian mapping.
e grid is separated into three dimensions: x, y, and z. ese three dimensions are responsible for locating everything that ever goes into 3D graphics. You see, in a 3D world you have a single point in space from which all other things are measured. is point in space is called the world origin. In Figure 1.2, you can see the world origin where the lines in bold intersect. Everything in 3D space is located from this point, which never changes. is is called the global coordinate system.
When working with 3D graphics, there are two types of coordinate systems: Y-up and Z-up. Y-up is generally the standard for animation, and Z-up is generally the standard for architecture and engineering. Why? Let’s look at the 2D grid system and see why.
A 2D grid is always at. e X-axis is horizontal, and the Y-axis is vertical. Pretty simple, right? Let’s make it more complex by adding the third dimension, Z. Now, if you are an animator you see the grid as a screen, facing toward your eld of vision. In this case, to your right is the positive X, to your le is the negative X. Straight up is the positive Y, and straight down is the negative Y. Where is the Z? e Z is away from you or towards you. erefore, as objects move away from you on the screen they are moving in the negative Z-axis. e arrows in Figure 1.3 are colorcoded, where X is red, Y is green, and Z is blue.
FIGURE 1.2 e Cartesian mapping system allows us to map coordinates in 3D space by choosing a single point from which all other locations are measured.
FIGURE 1.3 A manipulator handle in Maya. Most 3D so ware uses this colorcoding and appearance to give you the ability to move objects around in 3D space using a mouse. e arrows constrain the movement to one axis.
If you are an architect and you are laying out a plan for the design of a building, chances are that you are using a blueprint. When you are looking at a blueprint, the positive X-axis is to your right and the negative is to your le . e positive Y-axis is toward you, and the negative Y-axis is away from you. e positive Z-axis is up, and the negative is down. is is di erent from the animator’s view because you are looking down on the blueprint and making it 3D would extrude the building towards you.
For the sake of this book, we will always be working in the Y-up world. However, you should always be aware of the Z-up world and how to deal with information from it.
WHAT ARE THE COORDINATE SYSTEMS? ARE THERE MORE THAN JUST ONE?
Global and Local Coordinate Systems
OK, so now that we start to understand the setup of this coordinate system, let’s look at how the grid operates. e grid is an in nite set of coordinates that determines where a transform is. A transform is simply a point in space. at point in space can be moved, and anything that is connected to that transform will move with it. A transform has no volume, and it takes up no space. It is simply a way of determining where an object is in space. If we create an object in any 3D so ware, it will create a transform for us that is associated with that object. at transform will then be measured from the world origin in global space. erefore, the transform will be given three sets of coordinates, corresponding to the three axes in the following order: x, y, z. It is written in code form as (x, y, z). So we can say our transform here has a global space value of (0, 0, 0), shown in Figures 1.4 and 1.5.
If we move this object, the world space coordinates will re ect this movement. You can see that I have moved the object three units in the X-axis and now the global coordinates are (3, 0, 0). If I move it around in the other two dimensions, it will be located at (4, 1, 5). You can see that no matter where I put this object in the world, it will be located by its transform, which is a single point in space and will always have coordinates based on the world origin. is is how the computer calculates everything in 3D graphics; without this transform and world origin, movement and position could not be determined! (See Figures 1.6 and 1.7.)
FIGURE 1.4 Transforms with the translate, rotate, and scale listed in numerical value. ey are always read in values of (x,y,z).
FIGURE 1.5 A polygon sphere on the grid.
FIGURE 1.6 Numerical values entered into the transforms of pSphere1.
FIGURE 1.7 Manually transforming the object with a mouse; in Maya, this method uses what is called a manipulator.
WHAT IS LOCAL SPACE?
Hierarchies and Local Transforms
e global (or world) coordinate system is not the only way to locate an object. ere are relative locations for every point in space, especially if they are attached to another object. We call this the local coordinate system, which determines where an object is in relation to another object to which it is attached. You can think of this as we are “attached” to Earth. If you are living on Earth, then you are de nitely attached to Earth and your position is changing every second, relative to some point o Earth (let’s say the Sun). Because you cannot be separated from Earth (and if you did it would be very unfortunate for you), we consider you to be a “child” of Earth, and Earth is called your parent. In this relationship, known as a hierarchy, you inherit all the movements of the parent object. Your position, relative to Earth, is your local position because it is measured from your parent object. erefore, you might be standing still, which means that you aren’t moving relative to your parent, but your global position (measured from some other stable position like the Sun) would be in a constant state of ux because Earth is rotating around its own axis and around the Sun as well.
Just like this relationship between you and Earth, the relationship between a transform of an object and the pieces that make up that object is both global and local. An object in 3D graphics consists of sub-objects, which construct it in some way (we will explore this later); the sub-object points that construct it have positions that are relative to the object transform and to the world origin.
Hierarchies and coordinate systems may seem complex, and in fact, they can get quite di cult to understand. However, the basic notion of one object being connected to another should be quite familiar to us. For instance, look at your hand. Your hand can move around the space in your body while your body stands still. We can say then that your hand is moving in local space. However, if you start walking around and waving your hand, your hand is moving both in relationship to your body, and moving with your body. It is permanently connected. erefore, the wave is the wave no matter where you do it, but your body is moving in global space (and, hence, so is your hand). is idea of hierarchies should be natural to us because this is how our own skeletal system works.
HOW DO I CHANGE AN OBJECT’S POSITION IN SPACE?
Transforms
ere are three basic ways we can transform an object: translate, rotate, and scale. ese are considered the basic transforms. Each transform type has a pivot, or place from where the transform is calculated. Generally, the transform pivots are all in the same location, but some programs allow you to put each transform in di erent places. is pivot is essentially the transform node, as discussed before. What is really changing in any 3D object is the components of which that object consist, while keeping their relative positions from one another. e transform node is just a way of making them translate, rotate, or scale from a single point in space. In Figure 1.8, you can see that the points which make up this cube are in a di erent place than the pivot, which is indicated by the yellow box with the arrows sticking out (in Maya this is called a manipulator). All of the points of the cube in Figure 1.8 will move with this pivot when the transform object is moved. If the cube is rotated, the points making up the cube will be rotated around this point in space while keeping their relative positions to one another—that is, the cube will still be a cube, but it will rotate around the transform pivot point. e same goes for the scale. e points in space will scale inward or outward from the pivot point.
FIGURE 1.8 e points that make up the object, called vertices, inherit the transforms from the transform node, which transforms them in space relative to the pivot point, as indicated by the position of the manipulator handle.
Another random document with no related content on Scribd:
approaching a uniformed man would be almost instantly surrounded by one or two or even three squads who closed in to make the arrest. Philadelphia had the hunting of the bootlegger down to a fine point.
Mr. Todd Daniel, Superintendent of the Department of Justice for Philadelphia, has always been an ardent admirer of the A. P. L. In return, the League has supplied him on request with fifty to one hundred motor cars each month, and investigated as many as 1,000 cases which his staff would have been unable to handle. No wonder he admires them.
Surveillance such as this kept property damages in and around this great industrial center at a minimum. The Eddystone Munition Plant explosion occurred previous to the organization of the League. The Woodbury Bag Loading Plant, Woodbury, N. J., was so well covered that although a great many attempts to cause explosions and set fires were made with bombs and inflammable materials, they all failed of their purpose. No one can tell how much property loss was averted through the work of the Philadelphia division. It would be invidious to quote any, and hopeless to quote all, of the many letters of approval received from persons high in Government, political and commercial circles, complimenting the division upon its efficiency.
Needless to say, Philadelphia had her own share of causes celébrès. One of the most unique and interesting of these was that of the Philadelphia Tageblatt, a German daily newspaper prosecuted under the charge of seditious and disloyal utterances. In the fall of 1917, a raid was conducted by D. J. and A. P. L. upon the headquarters of this paper, at which time many files, books, papers, and so forth, were seized, with the result that warrants were issued for the editor and all his staff. When they were called for trial, members of the division were again used for the purpose of investigating the jury panel, as well as for the procurement of evidence essential to the case. In one item, this work took the form of securing through banking members, proofs of certain signatures without which the Government’s case would have been crippled.
These men were tried for treason, but were discharged for lack of evidence. They were subsequently prosecuted under a charge of conspiracy to hinder voluntary enrollment and for violation of the Espionage Act. On the latter charge, they were found guilty. Louis Werner, the editor, and his associate, Martin Darkow, got five years’ imprisonment each, Herman Lemke two years, Peter Shaefer and Paul Vogel, one year each.
The Tageblatt had been warned often against its unseemly utterances, but to no avail. It was a sheet of no great consequence, and about fifteen years ago was anarchistic. Then it turned to Socialism. When war was declared, it was outspoken against the Allies. After the declaration it became more cautious, but its columns were full of propaganda. It had no telegraph or cable service, but its policy was dictated by the selective choice of its editorial staff. Louis Werner was a naturalized citizen born in Germany. Darkow was a non-registered alien enemy and wrote the editorials. The president was Peter Shaefer, the treasurer Paul Vogel, and the business manager Herman Lemke. The trial for treason lasted only ten days. The second trial, for conspiracy, was more successful from the viewpoint of the law. Upon the stand, both Werner and Darkow were insolent. They will have time to think over all these matters in quiet for a while.
Red Cross frauds attracted some attention on the part of the League in Philadelphia, which investigated all sorts of fanciful rumors, as well as several schemes of fraudulent or nearly fraudulent or unworthy nature. One of these, purporting to collect for a central hospital, seemed at first to have merit; but when advertisements appeared offering solicitors a highly lucrative connection, the A. P. L. agents discovered that this was for the purpose of raising about $1,500,000—out of which a commission of twenty per cent was to be paid to the solicitors. A halt was called on this, but the same people got busy again about three months later with a campaign purporting to collect $1,000,000 for the care of “crippled negro soldiers.” There was a fund of about $10,000 which had been contributed by colored persons. Some of the people connected with
this movement were well-meaning and absolutely disinterested; yet in the background were others who appeared to be out for the coin. The campaign was closed down again. This is but a sample of other affairs of the same sort.
One of the notable Philadelphia affairs was that of Norman T. W , scholar, patent attorney, chess expert and draft evader. This case originated in Washington where he failed to appear for examination or to turn in a questionnaire. He asked to have his examination transferred to Philadelphia, so the whole matter was transferred to Philadelphia. On July 15, W was mailed his order for induction into the service and was told to report July 24, but he did not appear. Philadelphia A. P. L. then took on the matter.
W—— was the son of respectable Philadelphia parents and of good connections. Without doubt, he and his brother were shielded by their relatives and friends as long as possible. On November 8, the Philadelphia Division of the A. P. L. wired Washington stating that W —— had been apprehended. On November 16, 1918, he was sent to Camp Dix.
The public has some notion of the great plant for ship construction erected at Hog Island, near Philadelphia, by the United States Shipping Board. All sorts of stories came out regarding affairs at this shipping yard, and the charges were so direct and well-supported that Congress finally investigated the matter. The Philadelphia Division of the A. P. L. had some part in this investigation, which had to do with charges of extravagance, graft and waste of public moneys. There was one item, the employment of thousands of jitney drivers, which was severely criticised. These cars were employed by the Emergency Fleet Corporation to transport their workmen from their homes to the Island, since it was thought the regular transportation lines could not handle them. The charge was made that large amounts were collected by the jitney men from the Shipping Yard without rendering any service; the shipping yards, in turn, charged these amounts back to the Government. There were thousands of reports turned in by the operatives to D. J. on these
“jitney cases.” It was found that a good many men in authority were in the habit of ordering the drivers, after they had brought them down to the Shipping Yard, to go back home and place themselves at the disposal of the members of the families of the foremen or officers—the Government thus supporting a large number of private automobiles for salaried persons. The entire matter quieted down when the increased cost of tires and gas deprived the jitney drivers of their profits, and when competition came on through the installation of better service and equipment by the Philadelphia Rapid Transit Company.
There was no branch of the A. P. L. activities in Philadelphia so carefully handled as that having to do with the I. W. W. and other radical organizations. There were five Locals found and fifty-one revolutionary clubs with a total membership of 5,000, ninety per cent of whom were of foreign birth, absolutely opposed to all government and ever ready to overthrow law by revolutionary tactics.
The A. P. L. made a raid upon one club solely for the purpose of seizing literature and files. As a result of this, fifty I. W. W. agitators were dismissed from shipping yards and government plants. Some of these were in the Government Bag Loading Plant at Woodbury, in the shipping yard at Bristol, and in the Emergency Fleet Corporation at Hog Island. All these Philadelphia radicals contributed heavily to the defense fund of the I. W. W. members who were on trial in Chicago.
It was thought desirable to find any possible connection of German interest with these radicals. At one meeting the discovery was made that two men appeared and made a contribution to the foregoing defense fund. They came from a Fairmount German singing society —where they sang anything but American patriotic airs. The League kept close watch on all these radical organizations, so close that they have not dared to make any outright break. The slightest step out of the proper path would mean an immediate reckoning with men who have been rather stern in matters of justice.
After the Tageblatt case, which was the first case in the entire country resulting in a conviction under the indictments which were brought against Werner and his associates, the Grover Bergdoll case of mysterious disappearance is perhaps Philadelphia’s greatest contribution to detective literature. Indeed, there is still chance for a good detective in Philadelphia who can give bond for the production of the body of Grover C. Bergdoll, college athlete, wealthy young man-about-town, skillful mechanician, student of law, X-ray experimenter, radical editor—and draft evader. The Bergdoll brothers, Grover and Irwin, are known as the “slackers de luxe.” They were sons of a wealthy brewer, and having money, it seemed to them that they need not respect the law. They had shown their contempt for it before the draft reached out for them. Grover C. did not register, and Irwin failed to file his questionnaire. A. P. L. was set on their trail, but the young men had both disappeared. From that time until now neither of these men has been apprehended. Grover C. Bergdoll was seen in Mexico, was alleged to have been in the West on a ranch, was reported to have been in Spain, was said to have been seen in Western New York, and was reported also to have been in Philadelphia twice. Sometimes he would send a card to the newspapers just to tantalize the public, or to the officials whom he knew to be after him. Well, money is a present friend in times of trouble. For a time the Bergdoll mystery will remain a mystery. One of these days the life of the Bergdoll boys will fail to interest them. One of these days the law will lay its hands on them, and they will have to settle with the country which they have slighted and scorned and whose citizenship they do not deserve.
It may have occurred to readers of these pages that there was not enough blood and thunder stuff pulled off by the operatives of the A. P. L. It is quite possible that the Department of Justice men have had the harder load to carry in these more violent affairs, because quite often they are obliged to make the actual arrest, on warrants under evidence obtained by the A. P. L. One Philadelphia incident resulted in the killing of the man sought—a negro desperado who
carried several aliases but was best known in the saloon district as “Porto Rico.”
On Friday, November 8, two men of the League, in trying to locate a suspect, found two colored men in military uniform whom they followed. These gave up the whereabouts of two of their companions who were in a certain house. When found, these men claimed they had been drugged and robbed by some colored women there. It had been their present plan to wait there in the darkness until the women came back and then to kill them. The whole scene was in a tough part of town where the uniform of the United States does not belong.
Out of these proceedings the operatives got the address of four other men, one of these Porto Rico, who were supposed to be in the habit of robbing colored soldiers and other men in uniform. A certain saloon was visited by the operatives, and a few minutes after they appeared, a burly negro entered and was accosted as “Porto Rico” by the owner. The two operatives were C. H. Keelor of the League and Mr. Sprague of the Department of Justice. Keelor tapped Porto Rico on the arm and asked him for his card. The man got into action at once, kicked Keelor in the leg and struck Sprague, knocking him down. He made a leap to the open and pulled a heavy revolver, starting to retreat northeast on Lombard Street.
Operative Logan was on the opposite side of the street, and he now closed in. There was a shot fired, perhaps by a friend of Porto Rico. The latter raised his revolver and took aim at Sprague. Sprague was armed with a heavy holster gun and beat the negro to the shot, killing him with a bullet through the heart. Porto Rico fell, his revolver dropping from his hand, and such was his vitality that for a long time he struggled to reach the gun as it lay close by him. Sprague was cleared in court, as he shot obviously in self-defense. Charles Seamore, alias John E. Manuel, alias Porto Rico, was a notorious gun man. Beside his revolver he carried a razor and a number of 38-calibre cartridges. His registration card showed that he had registered under a false name. In almost the same place a little
while later a Philadelphia policeman was shot by a negro, who in turn was killed by a lieutenant of the police department.
In May, 1918, Major C. N. Green, U. S. Engineers, came into the League Headquarters of the Philadelphia Division and said he wanted assistance in organizing secret service work for plant protection and that he had been directed to the A. P. L. offices. Out of this later grew the connection of the A. P. L. with the Woodbury Bag Loading Plant.
At first there were about one hundred buildings on the 1,800 acres of unfenced land, about two hundred men being engaged in guarding the place. An organization of proved men had been made, which went directly into Government service. Five strikes were settled and no serious labor trouble resulted. It seemed marvelous that no disaster occurred in this plant. Time and again enemies attached time bombs to powder cars on their way to the munition plant. These cars were all stopped on an outside siding and searched, sometimes as many as thirty in one night. One time a bomb was found and two sticks of dynamite. A great deal of oily waste was found, which was no doubt attached in the hope that it might be set afire and so cause destruction of the car. There were two hundred and ten arrests made under charge of disorderly conduct, and one hundred under charge of trespassing. In each of these cases a conviction was secured. About two hundred violators of the Selective Service Act were put under arrest, and, as has been stated, thirty-five members of the I. W. W. were removed from the premises. More than one hundred and ten Austrians and Hungarians were discharged, and about two hundred aliens sent to the Department of Justice for examination. Over 1,500 investigations of suspects were made by the League, largely of men whose names seemed to proclaim them of German extraction. The record of this plant is unique, it probably being the only plant that has had so low a record of fires, explosions and accidents in all the history of our war work.
Guards often found people endeavoring to do damage. One such man had piled up scrap lumber and rags and was touching it off when fired upon by the guard. Two other attempts were made to destroy another one of the buildings. Not content with protecting the property from without, the A. P. L. even protected it from within. Charges were made of extravagant prices paid by the Government, a fact which strongly indicated graft somewhere. A corporation had made a bid to furnish boxes at $450 each, delivered. This bid was refused. Volunteer workers were called on to make these boxes. The work was done on Sunday, double time being paid—each man receiving $14 a day and even with such labor charges, it was found the boxes could be turned out at $17.25! This particular expenditure of money was stopped by the artless Ordnance Department. One or two chiefs were dismissed on the strength of reports from the A. P. L. of inefficiency, graft and irregularities.
This, then, all too briefly and lamely done in review, is the story of Philadelphia, which operated one of the very best amateur detective agencies the world has ever seen and which was a credit not only to Philadelphia itself but to every operative of the A. P. L. wherever he was located in the United States.
It only remains to say that in the monthly report for December, 1918, the Philadelphia Division turns in forty-eight bootleggers additional, two hold-up men, and nine soldiers absent without leave. It furnished D. J. in that month six hundred and forty-five men and sixty-five cars, investigated in that month two hundred and fifty-two draft evaders, seven hundred and forty-three cases from D. J. and various branches of the A. P. L., and 1,812 office assignments and Washington investigations. The Division closed the month of December, after the Armistice, going strong, with a membership of 3,438.
On the last day of the year, and after Philadelphia had finished all its reports for the year, there was a bomb outrage in that city in which lawless persons blew up the homes of three citizens. A call to the City Hall brought out every available detective and policeman, and
houses of other prominent men were placed under guard for that night. Once more the drag-net was put out to take in the lawless and all those of Bolshevik tendencies. The outrage was of such a nature that the Philadelphia papers carried editorials almost appealing to the American Protective League not to disband. Truly it will be missed in that city and in many another city of America. In this bomb outrage the lives of women and children were endangered. What are we to think of America for the future if at will the superintendent of police, a judge of the court, and a president of a chamber of commerce are to have their houses blown up as an act of vengeance of wholly irresponsible people such as no doubt committed this crime!
Early in January, 1919, Mr. Frank H. Gaskill, Assistant Chief, was promoted to be Chief of the Philadelphia Division for its closing days, Mr. Mahlon R. Kline resigning in his favor. The demobilization banquet of Philadelphia Division A. P. L. was held on the night of February 5, 1919, and it was as fine and ship-shape as all the other activities of the Division. It was hard for these men to say good-bye. Indeed, it is quite probable that many of the old Philadelphia A. P. L. members will organize, under another name, for purposes somewhat similar.
